In the ground simulation test of fire protection system for civil aircraft,the amount of airflow in engine fan cabin, engine core cabin, APU cabin and cargo is needed to be simulated in flight as the airflow has an important impact on test. Due to the important influence of flow accuracy to test, a kind of airflow simulated system based on PLC control and PID control algorithm is designed. The draught fan drove by frequency converter controls motor simulated the need of airflow that meets the ground test requirements.