Multi-frictional disks are employed to transmit the torque in speeding wet clutch, and the oil thickness within frictional disks could be adjusted for practical output speeding. As oil combined with a-hydrocarbon or polyester is getting widely used as lubricant and the speeding wet clutch works within hydrodynamic lubrication, mixture lubrication, boundary lubrication and contact situations, the authors have established the thermal analysis model for investigating the behavior of frictional disks in speeding wet clutch, which covers the power - law fluid model, Patir - Cheng average flow model, GT asperity contact model, oil film inertia and heat effects, mean energy equation, and heat conduction equation. The formulas in the model have been inferred in this paper. The numeral calculation and analysis for hydrodynamic lubrication and mixture lubrication have been executed.