Purpose:The COVID-19 pandemic may increase the development of psychiatric disorders, such as posttraumatic stress disorder (PTSD) among medical staff. A brief validated screening tool is essential for the early diagnosis of PTSD. The purpose of the present study was to evaluate the validation of a Chinese version of the Primary Care-PTSD-5 (C-PC-PTSD-5) and determine an appropriate cutoff score with optimal sensitivity and specificity for medical staff in China during the COVID-19 pandemic. Participants and Methods: An online cross-sectional survey was conducted on medical staff (n = 1104) from 17 medical institutions in Shanghai. Questionnaires comprising general information, medical-related traumatic event experiences, the PTSD Checklist (PCL-5), and C-PC-PTSD-5 were distributed to participants using the online Questionnaire Star electronic system. Internal consistency, convergent validity, and test-retest reliability were calculated. Receiver operating characteristic (ROC) analysis was performed to determine diagnostic accuracy and the optimal cutoff score of the C-PC-PTSD-5 for medical staff. Results: We included 1062 valid questionnaires for the analysis. Data of 838 traumatic experiences were analyzed. Internal consistency of the C-PC-PTSD-5 was satisfied (Cronbach's α = 0.756). The total score of the C-PC-PTSD-5 showed good test-retest reliability (r = 0.746). We found a strong correlation between the C-PC-PTSD-5 score and PCL-5 total score (r = 0.669, p < 0.001), which indicated good convergent validity. The ROC analysis showed an area under the curve of 0.81 ± 0.016. A cutoff score of 2 provided optimal sensitivity and specificity for the C-PC-PTSD-5 (sensitivity = 0.632, specificity = 0.871, Youden index = 0.503, and overall efficiency = 0.768). Conclusion:Our results indicated that the C-PC-PTSD-5 can be employed as a brief and efficient screening instrument for medical staff exposed to the COVID-19 pandemic. A score of 2 was identified as the optimal threshold for probable clinical PTSD symptoms.