Firstly,by taking the oil flow path of wet multi-disc friction clutch in marine as research object,the flu- id dynamic simulation of disk-separating process is conducted by means of dynamic mesh technique,and the distri- bution of oil film thickness between friction and steel disks is recovered.Secondly,on the basis of hydrodynamic lu- brication theory and Newton’s inner friction law,a mathematical model describing the towing torque of wet multi- disc clutch that contains friction plates with radial and circumferential grooves is established,and the analytical so- lutions of towing torque are obtained.Then,a parametric discrete model of oil film is established and the numerical solutions of towing torque are achieved by means of finite element method.Finally,the towing torque affected by groove form,drive shaft speed and oil temperature is analyzed.Calculated results show that (1) the numerical solu- tions of towing torque accord well with the analytical ones; (2) the groove form has a great influence on the towing torque; and (3) the towing torque of clutch increases with the increase of drive shaft speed and with the decrease of oil temperature.