Abstract： Objective To develop the submariners'Mental Health Risk Assessment Scale and evaluate its reliability and validity. Methods Through literature retrieval, personal interviews and open-ended questionnaire, the Submariners'Mental Health Risk Assessment Questionnaire was developed and the Cornell Medical Index (CMI) was used as the criterion to measure 1838 submariners. Results The exploratory factor analysis indicated that the Submariners'Mental Health Risk Assessment Scale or the Questionnaire had 10 factors, i. e. environment adaption, occupational recognition, interpersonal relationship, life satisfaction,working pressure, health concerns, self-regulation, sense of security, achievement and constraint. The Cronbach a-coefficient of the Questionnaire was 0.942, and α-coefficient of the 10 factors was between 0.581-0.890. The criterion correlation coefficients with MR scores and CIJ scores of CMI were 0.447 and 0.507 respectively, middle and high correlation could be seen between the factor scores and total scores of the Questionnaire (r=0.580-0.796, P<0.01). The score of mental health risk of 1838 submariners is 149.65 ±26.63. According to the percentile distribution of the 4 categories of mental health status by division of CMI, the percentiles of 32%, 68% and 92% were used as demarcation points, the corresponding scores were 136,161 and 187, which could be defined as the non-risk, low-risk, medium-risk and high-risk groups.Conclusions The Questionnaire seemed to have good reliability and validity to assess the mental health risks of submariners and could be widely used in the management of mental health of submariners in naval units.