The aim of this systematic review and meta-analysis is to evaluate the prevalence of depression, anxiety, insomnia, stress, PTSD, and distress in Chinese healthcare workers (HCWs) and the changes in prevalence before and after the peak incidence of COVID-19 in China. 20 cross-sectional studies assessing the aforementioned psychological outcomes were included. Eligible studies were searched from the following databases: PubMed, Scopus, and Web of Science. Comparative analysis based on the time period of the included studies was conducted to assess changes in prevalence before and after peak incidence. Additionally, subgroup analyses based on study quality, province, survey tools, gender and healthcare profession, frontline or non-frontline working status, and severity of psychological outcomes were conducted to evaluate the prevalence of outcomes across various study methods, geographic regions, and professions. The findings of this study suggest that the overall prevalence of depression, anxiety, insomnia, stress, PTSD, and distress before peak incidence were 36.2%, 34.2%, 22.4%, 31.3%, 9.8%, and 56.7% as opposed to 31.8%, 24.1%, 34.4%, 59.0%, 20.9%, and 40.7% after the peak. The higher prevalence of depression, anxiety, and distress prior to the peak incidence of COVID-19 in China and of insomnia, stress, and PTSD thereafter serve as evidence that the mental health decline of HCWs is dynamic and should be addressed with adaptive approaches that provide tailored treatments.