Objective To explore the mediating role of perceived stress among medical school graduate students in the relationship between the supervisor's guidance style and graduate students' general well-being. Methods In February 2021, a survey covering 208 graduates in a medical school was conducted using the supervisor's guidance style schedule, Perceived Stress schedule and General Well-Being schedule. The survey data were analyzed by spearman correlation analysis and mediation test. Results Graduate students scored (25.69 ± 5.92) for perceived stress, (77.30±13.64) for well-being, and (0.78±0.22) for their supervisor's guiding style. There was a significant positive correlation between perceived stress and supervisor's tendency to have a controlling mentoring style (r_s=0.16, P=0.026). A significant negative correlation between supervisor's guiding style and general well-being (r_s=-0.27,P<0.001) and between perceived stress and general well-being (r_s=-0.72,P<0.001) was found. The mediating effect of perceived psychological stress between supervisor's guiding style and graduate's general well-being was significant (95%CI=-13.40~-0.67), and the effect value (-6.64) accounted for 38.9% of the total effect value (-17.06). Conclusions Graduate students mentored by the supervisors who have a controlling mentoring style manifest a lower level of well-being. Graduate students' perceived stress mediates the relationship between their supervisor's guiding style and general well-being.