Abstract: The protection areas were divided mainly by the analogical empirical method at the early stage,which could not accurately measure the water quality indicators and the situation of reaching the standard requirements. Based on the Technical Standard for Drinking Water Sources Reserve Division（HJ 338-2018）,this paper carries out the research on the protection zone division of Chaihe Reservoir drinking water source,EFDC is used to construct a two-dimensional water quality model of Chaihe Reservoir. The changes of water age and pollutant migration in Chaihe Reservoir are simulated,and the eutrophication risk and main water quality in front of the dam are analyzed to evaluate the rationality of the division of water source protection zone. The results show that the water age of Chaihe Reservoir and the hydraulic retention period are the longest in the dry season under the three typical years of abundant,average and dry seasons. The migration and attenuation of contaminants in the reservoir are simulated,the results indicate that the water quality at the intake can reach the requirements,under the abundant,average and dry seasons,respectively. The division of the first-grade protection zone of Chaihe Reservoir can ensure the water quality of the intake,it is reasonable to use the analogy experience method to divide the protection zone.