In laser diode end-pumped Nd:YAG lasers,temperature distributions in rods under different heat-dissipation methods are calculated by the finite element method. Influences of two heat-dissipation methods,such as copper heat sink conduction method and water flow method on temperature of rods,are compared. Spherical aberration of thermal lens is presented. Based on the calculation results and ray-tracing theory,influences of two heat-dissipation methods on focal length of thermal lens distribution are compared quantificationally. Results show that the thermal lens focal length is smaller,focal length differences are shorter and spherical aberration is weaker,when using the heat-dissipation method with copper heat sink and TEC. And the thermal lens focal length is longer but focal length differences are larger and spherical aberration is more obvious,when using the water flow heat-dissipation method,Using the two heat-dissipation methods respectively,thermal lens distortion of a rod is simulated when the heat-dissipation is asymmetric.