Objective To investigate the effect of TGF-β1 on the invasion and metastasis of gastric cancer cells through JAK2/STAT3 signaling. Methods TGF-β1 at 0 μg/L, 1.0 μg/L, 10 μg/L, and 50 μg/L was added to BGC-823 cells by 10% FBS/F12. HE staining was used to observe cell morphology. RT-PCR and Western blot were used to detect the expression of JAK2/= and STAT3 as well as protein changes. Flow cytometry was used to detect apoptotic changes and cloning ability of cells. Results In the 0 μg / L group, the nucleus was elliptical, the shape was regular, and the cells were loosely arranged. As the concentration of TGF-β1 increased, the cells began to increase gradually, the cells were mostly round, multiple cells aggregated, and megakaryocytes or multinucleated cells appeared. The 50 μg/L group had the largest number of cells compared with the other groups. After treatment with 0μg/L, 1.0μg/L, 10μg/L, 50μg/L TGF-β1, the expression levels of JAK2 and STAT3 were found to be the lowest in the 0μg/L group, with the concentration of TGF-β1. The expression of JAK2 and STAT3 increased, and JAK2 was (0.618±0.114, 0.637±0.177, 0.919±0.351, 1.268±0.278), and STAT3 was (0.624±0.121, 0.647±0.162, 0.981±0.174, 1.297±0.264)(P＜0.05). The expression of JAK2 and STAT3 protein was the lowest in 0μg/L group, and the expression of JAK2 and STAT3 protein was the highest in 50μg/L group. The expression of JAK2 and STAT3 protein increased with the increase of TGF-β1 concentration, and the protein expression was proportional to the concentration (P＜0.05). After treatment with different concentrations of TGF-β1, the apoptosis was the most in the 0μg/L group, and the apoptosis was the lowest in the 50μg/L group, which decreased with the increase of the concentration. The apoptotic rate was (2.48±0.21, 2.31±0.19, 1.21±0.11, 0.818±0.08) (P＜0.05). The cell clone assay showed that the number of monoclonal clones of BGC-823 was the lowest in the 0μg/L group, while the number of monoclonal clones in the 50μg/L group increased significantly. With the increase of TGF-β1 concentration, the monoclonal formation rate of BGC-823 increased(P＜0.05). Conclusion TGF-β1 enhances the invasion and metastasis of gastric cancer cells by activating JAK2/STAT3 signaling pathway.