In this paper, a finite element model of an 808-nm high-power semiconductor laser single tube based on the actual package structure of the chip is used to obtain a reliable temperature distribution of the active layer during thermal simulation. The thermal distribution characteristics of the active layer during steady state operation are investigated by introducing various influence factors, such as ridge, copper layer on heatsink, and bonded wires. First, based on the simple finite element model, the effects of the stripe region, copper heatsink layer, and bonding wire on the average temperature of the active layer of the device were introduced and calculated. Then, these influence factors were simultaneously used to obtain the new model. The average temperatures of the active layer obtained with the simple model and the new model were 42.089 ℃ and 46.405 ℃, respectively. The average temperature of the active layer of the device calculated using experimental data of output wavelength variation with injection current was 41.708℃. Simulation results of the simple model showed an error of 11.26%. The error of simulation results of the proposed model is 0.91%. Finally, the thermal characteristics of several high-power semiconductor laser single tubes with the same package structure parameters and different conversion efficiencies and wavelengths were calculated to verify the accuracy of the simulation results.