Objective: To estimate the policy intervention effect of medical community reform on intra-county hospitalization rates in pilot counties from 2017 to 2018 in Guangdong Province，and to provide references for medical community and hierarchical diagnosis reform in other regions. Methods: Using the in-county hospitalization rate of each county in Guangdong from 2015 to 2018 as the dependent variable and including population size，GDP per capita and siphoning degree as control variables，it explored the effect of medical community reform on the in-county hospitalization rate of the pilot counties based on the difference-in-difference method. Results: The medical community reform policy was enacted in 2017 and had a positive net effect of 2.47 %on the inpatient hospitalization rate in the county by 2018，which was statistically significant (P＜0.05). Conclusion: The temporal trend of inpatient outflow in Guangdong counties is still severe，but the medical community policy can alleviate the phenomenon of patient outflow to a certain extent; the effect of the medical community policy is not immediate，and it is important to give the policy time and space to work and provide synergistic supporting support.