In this experiment, the action mechanism of the gene Ssc1 was studied in the process of interaction with plants through heterologous expression, subcellular localization and fluorescent PCR technology. It was found that the gene Ssc1 could enhance the pathogenicity of Botrytis cinerea through heterologous expression. Fusing the promoter, SP and CTP of Ssc1 with GFP and expressing in tobacco, it was found that the fusion protein could be secreted into plant cells and located in chloroplasts. Trypan blue staining and fluorescence detection found that in the early stage after inoculation and in the areas outside of the scab, GFP fluorescence could be detected in the tobacco leaves despite the trypan blue staining being negative. Additionally, it was proved by quantitative PCR that the gene Ssc1 was highly expressed in the early infection stages. Taken together, these results indicated that the effector Ssc1 was an important pathogenic factor, which could locate in chloroplasts and mainly play the role in the early stage during the interaction between S. sclerotiorum and plants.