In order to study the average velocity distribution law of liquid film seal flow field and its relationship with the shear stress of liquid-solid interface,the velocity calculation model of seal gap flow field with boundary velocity slip was established based on Couette flow model.By using the mixture homogeneous model and Schnerr-Sauer cavitation model,the radial,tangential and axial velocity distributions of the micro flow field at different axial positions of the liquid film at different speeds were investigated by numerical simulation under the two limit conditions of no slip (zero slip velocity) and no shear (maximum slip velocity) at the interface.The shear stress-velocity fitting model of the fluid groove interface was established.The results show that the tangential velocity of the liquid film is much larger than the radial and axial velocity,and the three-dimensional synthetic velocity distribution is mainly determined by the tangential velocity.The pres sure gradient of the flow field changes abruptly within 1 μm of the step in the groove region,but the flow fields in the non-groove region and the groove region are relatively independent,and the former can be regarded as simple Couette flow and the latter is reverse pressure gradient Couette flow.The magnitude of the adhesive shear stress at the fluid-solid interface is closely related to the boundary velocity slip of the liquid film,and when the interfacial shear stress in the groove region becomes smaller,the boundary slip velocity and the velocity in all directions of the flow field inside and outside the groove become larger,and the higher the speed,the greater the value.When it is not higher than 10 000 r/min,the cavitation effect has little impact on the overall average velocity field,but when the velocity is higher,it is necessary to quantify the cavitation effect and modify the shear stress-velocity fitting model.