We report the Thermal lensing characterization of face cooled Nd:YAG disk laser by considering the influence of heat sink, the simulating results are compared with the results without considering the influence of substrate. according to the pump energy distribution, thermal lensing of disk under Gaussian pump, super-Gaussian pump and uniform pump are simulated. Result revealed that depolarization loss due thermal stress is very low compare to rod-shape laser, the loss could be neglected in disk worked in fundamental mode, disk deformation is the mainly component to the thermal lensing.