Background: Globalization provides endless opportunities of travel and learning.As an example of global mobilization,China has recently become one of the largest host countries for foreign students in the world.International students face many challenges acculturating to and learning in a new country.These stressors could perturb abroad student′s mental well-being（MW）.Limited research has been undertaken into acculturation stress（AS）and MW among international students in China;wherefore to improve or maintain mental health it’s necessary to expand the evidence.Objectives: Accordingly,the present study addressed the following objectives:（1）to investigate the AS status among international students in China;（2）to investigate the MW status of international students in China;（3）to assess the association between AS and MW in international students living in China and to know the main acculturation stressors.The ultimate goals are to improve the understanding of acculturation stress and its relationship with MW and make the data collected here available to all stakeholders for future plans or interventions within international students living in China.Methods This is a cross-sectional study with survey methodology.The data was collected in China via the online questionnaire platform.self-reported questionnaire was the tool to gather the data,concerning the participants’ acculturation stress（measured by the 36-items Acculturation Stress Scale for International Student（ASSIS））,mental well-being（measured by the 14 Items-Warwick Edinburgh Mental Wellbeing Scale（WEMWBS））,sociodemographic information and other covariates.Descriptive statistics was reported to summarize the general characteristics of participants.Pearson’s correlation was employed to explore the association of acculturation stress（overall and seven sub-scales）with mental wellbeing.Linear regression analysis was conducted to determine the relationship between acculturation stress（and its subscales）and mental well-being after adjusting for potential confounders.All statistical analyses were performed using SPSS 26.0 version,and a two-sided P value < 0.05 was considered statistically significant.Results: The mean age of the international students participating in this study was 27 years old（SD 4.5）.Among all of the respondents,87（40.65%）were male,and167（78.04%）had been living in China for less than 5 years.The mean of acculturation stress score was 89.66（SD 25.06）and that of mental wellbeing score was 48.73（SD 11.06）.The number（proportion）of samples in the low,moderate and high acculturation stress groups was53（24.76%）,156（72.89%）and 5（2.33%）,respectively;the number（proportion）of samples in the low,moderate and high mental well-being groups was 52（24.29%）,134（62.61%）and 28（13.08%）,respectively.Multiple Linear regression analysis indicated a negative relationship between the total acculturation stress score and mental well-being score（β =-0.107,95% CI=（-0.16,-0.06）;p<0.05）after controlling for confounders including age,gender,length of stay in China,relationship status,highest educational qualification,moving motivation,academic performance,social activity,having Chinese friends,and counseling program/psychological support.Among the seven components of acculturation stress,four sub-scales（perceived discrimination,homesickness,perceived hate and fear）were significantly and negatively associated with mental well-being（adjusted β was-1.409,-1.377,-1.874,-2.258,respectively;all P <0.05）,and the other three（culture shock,guilt,miscellaneous）did not have significant impact on the outcome（all P >0.05）.Furthermore,stratified regression analysis of the association between acculturation stress and mental well-being was conducted,showing that the above association was more apparent in certain levels,i.e.,among international students who were single/never married or divorced/separated,among Ph D students,among students who achieved good academic performance,and among students who were not enrolled in and did not need counseling program/psychological support.At last it was seen that the educational level acquired prior to moving to China,the frequency of social activity and the relationship with locals could also significantly impact on the international students’ mental health.Conclusions: Findings from this study reveal that the majority of international students in China are in moderate level of acculturation stress and mental well-being.A higher level of acculturation stress could be associated with a lower level of mental well-being,and the above association is especially apparent in certain groups of international students（e.g.,students who are single/never married or divorced/separated,Ph Ds,with good academic performance）.Subcomponents of acculturation stress including perceived discrimination,homesickness,perceived hate and fear,are the major stressors that are significantly and negatively associated with mental well-being.These findings could build on the existing knowledge about dealing with the acculturation stress among international students,especially towards specific stressors and certain groups of students.It was also seen in this research that the educational level acquired prior to moving to China,the frequency of social activity and the relationship with locals could impact on mental well-being scores of international students.This reinforces the idea that preparing the university environment in the best way will allow the adaptation of the foreigner to the new destination,making it harmonious and low in stress what could in a future lead to a positive impact on mental health.At last but not least,this leads us to think that it is necessary to continue investigating more in this field,to determine what would be the best measures or action plans to improve the acculturation process in international students,in order not to increase stress levels and therefore ensure a positive mental health.