Objective： To discuss the application of microsimulation model in forecasting the change of medical insurance risk-pooling fund in Kunming city. Methods.. Taking the SASS. 2 software as the platform, we constructed a microsimulation model for urban employees＇ medical insurance in Kunming city using computer simulation technology and ARENA simulation software. Results： The construction process included 4 steps： （1） to confirm the simulation object; （2） to construct the micro data file; （3） to design the system and to program; （4） to run the program and forecast the result. The system mainly consisted of population status module,action module and policy module. Conclusion： The present model complies with the latest type distribution of employees in Kunming, and its simulation result can reflect the effectiveness of medical insurance policy in recent years