OBJECTIVE: To establishment the Sense of Security Scale for Medical Staff and test its reliability and validity. METHODS: The pre-test version scale was formulated through methods of literature review, semi-structured interviews with clinical medical staff, discussion with members of research groups, and consultation with medical experts. A total of 350 and 403 medical staff who worked in a tertiary A hospital in Guangdong Province were selected as the prediction and the verification samples, respectively, by convenience sampling method. The reliability and validity of the final version scale were tested by item analysis, exploratory factor analysis and confirmatory factory analysis. RESULTS: Through item analysis, it was determined that the scale was mainly composed of 24 items. Exploratory factory analysis extracted five characteristics: environmental factors, patient factors, self factors, organizational management, and social support, that explained 72.8% of the total variation. The results of confirmatory factory analysis showed that the ratio of chi-square to degree of freedom was 2.851, the mean square error of approximation was 0.068, the standardized mean square residual was 0.078, the goodness of fit index was 0.883, the normative fit index was 0.904, the comparative fit index was 0.935, the non-standard fitting index was 0.924, and the incremental fitting index was 0.936. The results of reliability and validity test showed that the total Cronbach alpha coefficient, Spearman-Brown coefficient and retest reliability were 0.939, 0.967 and 0.808, respectively. The item reliability of each item was 0.420-0.814, the composite reliability was 0.775-0.920, the content validity ratio was 0.904, the convergent validity was 0.514-0.741, and the discriminative validity was 0.717-0.861. CONCLUSION: The reliability and validity of each dimension of the Sense of Security Scale for Medical Staff is good, and it can be used as an evaluation tool to measure the sense of security in medical staff.