Abstract: The feasibility of the high oxidative activity and efficient light energy utilization mechanism of chloroplasts photoreaction system used for lignin degradation had been studied in this paper to look for a new lignin degradation method.Photoreaction enzyme system was separated from plant photosynthetic tissue, and its effect on lignin degradation and its function conditions were investigated.Moreover, the effects of small molecules and illumination on lignin degradation efficiency were investigated.The results demonstrated that Photoreaction enzyme system could effectively degrade lignin in lignocellulose.The appropriate function condition was at pH6.0 and 45℃, and illumination was necessary.In this case, the lignin degradation rate was 27.7% and cellulose dissolution quantity from residue was 104.6mg·g～ (-1) when 1mg enzyme protein acted on 1.20g paper mulberry lignocellulose for 3h under the sunlight (noon, July) , which was respectively 2.9 times and 4.4 times than in dark place, and 1.9 times and 1.6 times than those of laccase respectively.Constituention or electronic transfer components or analogue could improve lignin degradation efficiency.In conclusion, photoreaction enzyme could effectively utilize luminous energy to degrade lignin and promote the release of cellulose during the subsequent zymohydrolysis process.