In order to improve the conversion efficiency of GaSb thermophotovoltaic cells, p+-GaSb window layer was introduced into the cell structure. The effects of bases, substrate temperature and reactant source temperature on the properties of p+-GaSb films were studied, the thickness and doping concentration of p+-GaSb window layer in the cells were optimized. The experimental results show that the structure and electrical properties of p+-GaSb films are affected by the bases and temperatures, and the performance of the cells can be improved significantly with thin and high doping p+-GaSb layers. Through the measurement and simulation, the conversion efficiencies of the thermophotovoltaic cells reaches 9.49% (AM1.5 measurement) and 20.34% (AFORS-HET simulation).