On basis of the thermal radiation equilibrium principle,and considering the relations between laser power density,photovoltaic cell temperature and photoelectric conversion efficiency,the thermal radiation equilibrium model of photovoltaic cell under space thermal radiation is established.By using this model,the effect of laser power density and photoelectric conversion efficiency on the cell temperature can be analyzed.By correcting the original photoelectric conversion efficiency model from the temperature,a new model is obtained.Based on the thermal radiation equilibrium model and modified photoelectric conversion efficiency model,the relations between laser power density,cell temperature and photoelectric efficiency can be analyzed by using MATLAB software.The simulation results show that,with the increase of laser power density,the cell temperature will keep rising,but the photoelectric efficiency and output power density will firstly increase and then decrease.And the cell temperature in daytime is higher than at night,and the photoelectric efficiency in daytime is lower than at night.