Objective：The current study aims to investigate the effect of 4 - hydroxysalicylaniline（HDS）on the proliferation and apoptosis of T-lymphoblastic leukemia cells，Jurkat and Hut-78，in vitro and in vivo. Methods：In vitro，HDS was used to treat Jurkat and Hut-78 cells with different concentration gradients. The CCK-8 assay and colony formation assay were used to detect the effect of HDS on cell proliferation. Cell cycle changes were detected by flow cytometry，and the expression levels of cycle-related proteins were detected by Western blot. The apoptosis level was detected by flow cytometry，and the expression levels of apoptosis-related proteins were detected by Western blot. DNA damage was detected by γ- H2AX immunofluorescence staining，and the expression levels of DNA damage related proteins were detected by Western blot. In vivo，the mouse T - cell lymphoblastic leukemia tumor model was constructed by subcutaneous injection of Jurkat cells，and HDS was injected to observe the effect of drugs on tumor volume and body weight of mice. HE staining was used to observe the morphological changes of tumors after 13 days of HDS creatment. Immunohistochemical staining of Ki67 and γ -H2AX protein was used to analyze the effect of drugs on cell proliferation and DNA damage in tumors. Results：In Jurkat and Hut-78 cell lines，HDS could induce cell cycle arrest at S phase，induce cell apoptosis，and block DNA damage repair through phosphorylation of CHK1/CHK2 signaling pathway，both in vitro and in vivo. HDS inhibited T-cell lymphoblastic leukemia tumors，and it had no obvious toxicity to mice. Conclusion：HDS can be used as a potential anti - T - celllymphoblastic leukemia drug. The effect of HDS on T-cell lymphoblastic leukemia may be accomplished by interfering cell cycle and apoptosis，and DNA damage repair through CHK1/CHK2 signaling pathway.