This study used systematic collection of all legal documents related to infectious disease prevention and control systems in Zhejiang and Shanghai， covering the situation of the main departments （institutions） and its clear situation according to the legal liability clause， and comprehensive calculation of the supporting degree of the laws for infectious disease prevention and control systems and Spearman correlation and linear regression were used to analyze the relationship between supporting degree and incidence of infectious diseases. In both Zhejiang and Shanghai， the degree of active improvement of laws and regulations related to infectious disease prevention and control system was continuously strengthening， from 58.5% in 2000 to 76.8% in 2017 in Zhejiang， from 68.0% in 2000 to 71.6% in 2017 in Shanghai. There was a negative correlation between the support degree of the laws on infectious diseases prevention and control system and incidence of infectious diseases （P＜0.05）. The degree of support of the laws of Zhejiang and Shanghai on the infectious disease prevention and control system had improved and preliminary effect was presented. Shanghai had better effect than Zhejiang province， and both provinces had room for improvement. This study was scientifically feasible for the quantitative method of legal support.