The invention discloses a robinia pseudoacacia Subtilisinl gene. After robinia pseudoacacia total RNA is extracted and subjected to reverse transcription, cDNA is compounded. By adoption of the Race technology, the robinia pseudoacacia Subtilisinl gene sequence (SEQ ID NO:1) is obtained, and the sequence is subjected to full-length amplification to obtain the robinia pseudoacacia Subtilisinl gene. The robinia pseudoacacia Subtilisinl gene obtained by the invention is mainly expressed in flowers and leaves of robinia pseudoacacia, and the expression quantities in roots, stems and pods of the robinia pseudoacacia are relatively low. The expression quantity of the robinia pseudoacacia Subtilisinl gene in aged tissues is higher than that in tender tissues, which shows that the gene is a plant protective mechanism used for delaying tissue aging. Cloning of the gene lays a theoretical foundation for breeding of the robinia pseudoacacia and other forest tree types.