In order to achieve the stable and reliable propety of adjustable time-lapse self-closing faucet under the the condition of meeting water saving,this paper designed a multi-port valve. Based on the principle of orifice throttle,it analyzed the characteristics of faucet's flow and got the structure parameter of valve spool.Then the paper used the fluent to simulate the internal flow field of faucet, analyzed it's characteristics and optimized the spool entrance angle to improve the the feature of internal flow field of faucet.The results showed that the constant flow design of valve spool in the actual condition can ensure the water saving requirement of faucet and have higher practical value.When the inlet angle of valve spool is 25°, the performance of faucet is optimal. Theresult can provide a theoretical basis for the next study of delay part.