It is commonly known that the performance of electrocatalysts is largely influenced by the size,morphol-ogy,composition,and crystalline phase of noble metal nanocrystals.However,the limited reserves and high cost of noble metals largely restrict their industrial applications.Along with the development of characterization techniques,theoretical calculations,and advanced material synthesis methods,modu-lating the electrocatalytic properties of noble metal nanocrystals at the atomic scale (e.g.,monolayer/sub-monolayer,single-atom alloy,ultrafine structure) has been flooding out.Engineering noble metal nanocrystals at the atomic level could not only immensely improve the noble metal atom utilization effi-ciency and lower the cost,but also boost the catalytic performance.In this review,we summarize the recent advanced progresses of regulating the noble metal nanocrystals at the atomic scale towards energy conversion application.Then,the challenges and perspectives of designing noble metal nanocrys-tals at the atomic scale in the future are discussed and considered.It is expected that this review will inspire scientists to further study precious metal-based materials for energy-oriented catalysis.