Abstract: In order to study the genes that sense stress signals under drought conditions in Amorpha fruticosa and maintain their functional roles in tolerance through physiological and biochemical regulatory pathways, which can provide a candidate gene for drought-resistant breeding of Amorpha fruticosa. The transcriptome data of Amorpha fruticosa under drought stress were analysed, the expression of Ascorbate Peroxidase（APX2） gene, which is a system of reactive oxygen balance, increased significantly with the time of drought stress, and the AfAPX2 gene of Amorpha fruticosa was cloned, and a seamless cloning technique was used to connect to the starter vector（pQB-V3）, and a Gateway system LR was developed. The target gene was constructed into the expression vector by Gateway system LR reaction, and transformed into Agrobacterium rhizogenes EHA105 by electroshock method, and Agrobacterium-mediated transformation of tobacco（Nicotiana tabacum） was adopted, and the healing tissues were cultured into seedlings of T₀ generation, and seeds were harvested and planted to study the correlation between them and drought stress. The results showed that AfAPX2 gene expressed protein was homologous to APX2 from Arabidopsis and rice, and also had the structural domain of peroxidase, which was hypothesized to enhance plant stress tolerance through the ROS pathway. The secondary structure of AfAPX2 protein had 13 α-helices, 17 β-folds, 4 β-turns, and multiple irregular curls, and the tertiary structure of the AfAPX2 enzyme had a ferric ion. The tertiary structure of AfAPX2 enzyme has a binding site for iron ions. Under drought stress and restoration of water supply after stress, the leaves as well as plants of overexpressing AfAPX2 gene lines were significantly more luxuriant than those of the wild type. In this study, we found that trans-AfAPX2 gene-positive plants showed enhanced tolerance to natural drought stress and improved drought tolerance in tobacco, suggesting that AfAPX2 may play an important regulatory role in response to drought stress. It was further verified that the up-regulated genes in the drought stress transcriptome of Amorpha fruticosa were related to it, and the relevant genes for improving drought tolerance could be found. Overexpression of AfAPX2 in tobacco showed that transgene-positive plants showed enhanced tolerance to natural drought stress and improved drought tolerance in tobacco, suggesting that AfAPX2 may play an important regulatory role in response to drought stress. It was further verified that the up-regulated genes in the drought stress transcriptome of Amorpha fruticosa were related to it, and the relevant genes for improving drought tolerance could be found. It can be used as a candidate gene for breeding drought resistance in Amorpha fruticosa, which lays a solid theoretical foundation for its genetic improvement and resource utilization.