ObjectiveExploring the impacting factors associated with the three dimensions of occupational burnout including emotional exhaustion, depersonalization, and reduced professional accomplishment and the moderating role of social support among primary mental health medical staff.MethodsIt was a cross-sectional study. Convenience sampling method was used, and self-report data were collected electronically between February 14, 2023 and August 31, 2023 from primary mental health medical staff working in communities in Shanghai. A total of 371 valid questionnaires were collected. The occupational burnout was evaluated by the Chinese version of the Maslach Burnout Inventory General Survey (MBI-GS), which consists of three dimensions: emotional exhaustion (EE), depersonalization (DP), and reduced professional accomplishment (PA). Levels of social support were measured by the social support rating scale (SSRS). Multivariate linear regression was used to analyze the effects of demographic and occupational factors on EE, DP, and reduced PA scores. Regression-based statistical moderation effect was conducted with the PROCESS macro of SPSS, to explore the potential role of social support as a moderator.ResultsCompared to primary mental health medical staff in Beijing and Chengdu, the staff in Shanghai had a higher proportion of permanent contracts, a greater percentage of doctors, and a higher level of education. Multivariate linear regression showed that perceived workload, job satisfaction, and professional background predicted the level of EE. Team cooperation status, perceived workload, and job satisfaction predicted the level of DP. Team cooperation status and job satisfaction could predict PA scores. Social support significantly moderated the effects of workload on EE and DP. A weaker association between workload and EE was observed in staff with high-level social support than in low-level ones (simple slope 0.81 vs 1.53, P=0.001). Similar moderating effects were found between workload and DP (simple slope 0.45 vs 1.25, P=0.001).ConclusionBoth demographic and occupational factors predicts burnout levels. Social support negatively moderates the positive effects of workload on EE and DP levels. Teamwork within community mental health service should be enhanced, with a focus on the professional background of primary mental health medical staff and the level of social support in the work environment. Additionally, it is important to address the high prevalence of perceived heavy workload and low job satisfaction among these staff, to improve the effective management of patients with severe mental disorders in the community.