Monocrystalline silicon and single junction GaAs/Ge solar cells irradiated by 16 ns pulse-duration with the laser at 1064 nm wavelength for different fluences (energy densities) were studied. It was found that solar cell is easily damaged when laser spot was focused on the metal gridlines, meanwhile, monocrystalline silicon solar cell was almost undamaged when laser spot was focused on the surface, GaAs/Ge solar cells’ performance didn’t decrease greatly. Theoretically, the damage of nanosecond pulse mainly commons heat and dynamics effects. The high temperature melts and gasifies materials and the dynamical effect is along the laser’s transmitting direction vertical to the surface of materials. Investigation also indicates that monocrystalline Si cells and the thick germanium base intrinsically absorb 1064 nm strongly, while the GaAs/Ge is transparent to 1064 nm, The melting point of germanium material is lower than that of silicon, so its damage threshold is lower. These experimental conclusions were proved and verified by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).