Triple-junction GaAs photovoltaic cell is an ideal component for the photoelectric conversion module of laser wireless energy transmission system with resistance to hard light, high photoelectric conversion rate and good temperature characteristics. Based on the spectral response curves of the triple-junction GaAs photovoltaic cell, the impact of different ration of lasers on the conversion efficiency of three-junction GaAs photovoltaic cells was studied by using 532, 808 and 980nm lasers with the total power of 2W. The result shows that the conversion efficiency of triple-junction GaAs photovoltaic cell is 33.549% when the ratio of 532, 808 and 980nm is 7∶8∶5, which is useful for improving the conversion efficiency of the triple-junction GaAs photovoltaic cells.