BACKGROUND: In recent decades, mental health and stress among medical students have become a global concern. Currently, China lacks a scale specifically designed to assess stress levels in medical school settings. This study aims to cross-culturally translate and adapt the Perceived Medical School Stress (PMSS) Scale into Chinese, evaluate its psychometric properties in medical schools, and analyze the associated factors of medical students' stress levels. METHODS: Data collection for the Chinese version of the PMSS was conducted from October to November 2023, among medical students from selected medical schools in North and East China. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to evaluate the underlying factor structure. Content validity was assessed using the Content Validity Index (CVI). Criterion validity was evaluated with the Chinese version of the Perceived Stress Scale (PSS). Internal consistency was assessed by calculating Cronbach's alpha coefficient, McDonald's Omega coefficient, and test-retest reliability. Additionally, relationships between medical school stress and general demographic characteristics, insomnia severity, and self-efficacy were examined. RESULTS: The final Chinese version of the PMSS supports a two-factor structure with 13 items, defined as "psychological stress and environment" and "resilience and expectations." The scale's Content Validity Index (CVI) was 0.980, with a criterion validity of 0.767. The Cronbach's alpha coefficient was 0.911, McDonald's Omega coefficient was 0.914, and the test-retest reliability was 0.794. Medical school stress levels showed significant differences based on gender and educational background (P <
0.05). Stress levels were positively correlated with insomnia severity and negatively correlated with self-efficacy. CONCLUSIONS: The Chinese version of the PMSS is a reliable and valid tool for assessing stress levels among medical students in Chinese medical schools. Female students and those pursuing graduate degrees report higher levels of medical stress. Insomnia severity and self-efficacy significantly influence stress levels among medical students.