Objective of this investigation is to further analyze the cardiac function status change by phonocar diogram during mixed anesthesia which is conducted by midazolam, skelaxin, fentanyi and propofoL The results show that blood pressure, heart rate, amplitude of R wave and T wave, amplitude of first heart sound (Si) and second heart sound (52) about 37 subjects after anesthesia decrease compared with baseline, while the. ratio of first heart sound and second heart sound (Si/S2) and the ratio of diastole duration and systole duration (DIS) increase. Our study demonstrates that phonocardiogram as a noninvasive, high benefit/cost ratio, objective, repeatable and portable method can be used for the monitoring and evaluation of cardiac function status during anesthesia and operations.