BLH3 (Bel1-like homeodomain gene3) plays a crucial role in plant development. However, its involvement in the salt stress response has not yet been studied.In this study, we investigated the molecular mechanism underlying the response of LpBLH3 to salt stress in Lilium pumilum ( L. pumilum) using various techniques, including quantitative PCR (RT-qPCR), electrophoretic mobility shift assay (EMSA), dual-luciferase reporter assay (LUC), yeast two-hybrid (Y2H), and luciferase complementation imaging (LCI).RT-qPCR analysis revealed that LpBLH3 is most highly expressed in the leaves of L. pumilum. The expression of LpBLH3 peaks at 24 or 36 hours in the leaves under saline stress. Under various treatments, compared to the wild type (WT), the LpBLH3 overexpression lines exhibited less chlorosis and leaf curling, higher accumulation of proline and chlorophyll, lower levels of reactive oxygen species, and increased activity of antioxidant enzymes.The roots and stems of LpBLH3 overexpression lines exhibited significantly higher lignin content compared to those of the wild type (WT). EMSA and LUC analyses confirmed that LpBLH3 can bind to the promoter of LpABI5. Additionally, yeast two-hybrid (Y2H) and luciferase complementation imaging (LCI) analyses demonstrated that LpBLH3 interacts with LpKNAT3. LpBLH3 enhances the plant’s salt tolerance through the ABA pathway and lignin synthesis.