Objective: To investigate the mental health status of prisoners, provide reference for supervision safety and reconstruction quality. Methods:35604 prisoners in 25 units in H province were tested with SCL-90, and the results were comparable. Results:(1) Mental health of prisoners. The total detection rate(180 points or more) of this survey was 32.9%, among which somatization, compulsion, depression, anxiety and other factors were prominent.(2) Comparison of mental health status of prisonerswith different genders. There was a significant difference between the average total score and the average score of 9 factors(p<0.001), and the mental health level of male prisoners was lower than that of female prisoners.(3) Comparison of mental health status between felons and non-felons. The average score and factor score of felons were significantly higher than those of non-felons(p<0.001).(4) Comparison of mental health status of prisoners with national norms. The average total score and average factor score of prisoners were significantly higher than the national normal adult norm (p<0.001).(5) The scl-90's average score of male prisoners was 2.02±0.82, while that of female prisoners was 1.75±0.51. Conclusion: The scl-90 general survey can grasp the mental health status of prisoners as a whole, which is of important reference value to the mental correction work of prisoners.