Abstract: In the preparation process of heterojunction（HJT） solar cells,light injection annealing after lowtemperature curing process can improve the photoelectric conversion efficiency of solar cells. This paper investigates the effects of light injection annealing on the n-surface of HJT solar cells,including the time and temperature of light injection annealing,as well as the effect of bifacial light injection annealing on the improvement of photoelectric conversion efficiency. Additionally,the effects of light injection annealing on the efficiency enhancement of HJT solar cells at different levels of photoelectric conversion efficiency are analyzed.The results show that:1) With the increase of annealing time for light injection,the increase in the photoelectric conversion efficiency of HJT solar cells first increases and then remains basically stable;2) As the annealing temperature of light injection increases,the increase in the photoelectric conversion efficiency of HJT solar cells first increases and then decreases;3) Both sides of the solar cell undergo light injection annealing treatment,which cannot achieve the effect of superimposed improvement in photoelectric conversion efficiency;4) The enhancement effect of light injection annealing on HJT solar cells with low photoelectric conversion efficiency is better,mainly because there are more defects inside and on the surface of such solar cells.