Abstract: Objective To study influences of organization justice,occupational risk,and occupational stress on mental health and to provide evidences for improving mental health among medical staff.Methods With multi-stage stratified random cluster sampling,3946 medical staff were recruited from hospitals and public health institutions of various administrative degrees in 3 cities and 3 counties with different economic development level in Liaoning province and investigated with Kessler 10 Psychological Distress Scale(K10)and Organizational Justice Questionnaire.Linear regression was adopted in data analyses.Results The average K10 score for all the staff was 20.24±0.13 and the staff working in urban facilities,aged 31-40 years,engaged in nursing service,working in emergency department,with higher education,and with lower economic condition had a higher K10 score.The average K10 score was positively correlated with organizational justice,occupational risk,and occupational stress significantly among the medical staff.Organization justice could explain 16.21% of the variance in K10 score,followed by professional risk and pressure source(6.68%)and the type of work showed the lowest explanatory power(2.31%).The distribution and leadership justice showed positive influences on K10 score(P<0.001).Conclusion Distribution and leadership justice need to be promoted in medical and public health institutions to improve mental health among medical staff in the facilities.