Focused on pressure loss of throttling groove used in engineering machinery of flow control valve port,the pressure loss is comparativly analyzed by using theoretical calculation and computer flow dynamics (CFD) technology.The results show that,when spool displacement of flow control valve is constant,pump output flow rate is larger,and then the loss pressure of inlet and outlet is larger.When main pump output flow rate is constant,spool displacement is larger,and then the loss pressure of inlet and outlet is smaller.