:For the influence of the internal leakage of continuous rotary electro-hydraulic servo motor on its lowspeed performance，based on the theory of fluid mechanics，finite element analysis method was adopted to study theinternal flow field distribution of continuous rotary motor and obtain the changing rule of the inside leakage of themotor. The 3D model of the internal flow field of the motor was established by UG software. The high quality O-gridwas generated by the ICEM CFD software. Then mesh models were imported into finite element software ANSYSCFX，and reasonable boundary conditions was seting up. The motors’ internal leakage distribution regularities wereobtained under different pressure and gap of the vane through simulation，results show that the greater pressurebetween high and low pressure chamber，the greater the fluid flow rate through the tip clearance，and the internalleakage increases with the pressure difference increasing，which lay the foundation for studying the effect of internalleakage on the low speed performance of the motor.