Objective: To analyze the status of personnel in occupational disease prevention and treatment institutions in Hunan Province, China, from 1996 to 2015, to predict staff composition using grey model (GM) (1, 1) , and to provide a scientific basis and reference for optimizing human resource planning of occupational disease prevention and treatment in other provinces and regions and promoting the service capacity of the institutions. Methods: The data of the staff in occupational disease prevention and treatment institutions in Hunan Province, China, from 1996 to 2015 were obtained from the established basic information management system. The descriptive analysis method was used to analyze the dynamic changes in number and composition of the staff and the GM (1, 1) was used to predict the staff composition. Results: The numbers of the staff members in 1996 and 2015 in occupational disease prevention and treatment institutions in Hunan Province, China were 1591 and 1429, respectively. In the twenty years, the main education level of the staff transformed from "technical secondary school education and non-academic qualifications" to "bachelor degree or above and college degree"; the main major of the staff transformed from "other majors" to "public health and clinical medicine"; the proportion of the staff members without professional titles changed from >1/3 to 5%; and the proportions of the staff members with senior, intermediate, and junior professional titles were steadily rising. GM prediction showed that the proportions of highly educated staff members in 2018 and 2020 would be up to 41.00% and 45.61%, respectively; and the proportions of the staff members with a major in public health in 2018 and 2020 would be up to 44.15% and 46.60%, respectively. Conclusion The staff in occupational disease prevention and treatment institutions in Hunan Province, China, in the twenty years have slight changes in staff size and great improvement in staff quality, which is beneficial to sustainable development of the occupational disease prevention and treatment undertakings. The education level and major will be further optimized in the next five years.