Effects of heat transfer on grid lines of triple-junction solar cell irradiated by 1 070 nm CW laser were studied through the damage on triple-junction solar cell irradiated by laser with electroluminescence test. Three-dimensional model based on germanium solar cell was constructed with finite element analysis software COMSOL to simulate temperature distribution on triple-junction solar cell irradiated by CW laser. The results indicate that the top-cell of triple-junction solar cell is slightly damaged at the laser power density 72.5 W/cm2 and continuous irradiation time 41 s and the damaged region is firstly distributed along the grid line. The temperature of germanium solar cell in the simulation model has increased to 1 318 K and the grid lines which has high heat conduction rate result in the anisotropic heat transfer direction. The experimental results are well explained by the simulation model.