Objective To investigate the effect of inhibition of MEX3A gene expression on proliferation and apoptosis of bladder cancer cells by lentiviral-mediated RNA interference technology. Methods The shRNA lentiviral vector targeting MEX3A gene was constructed using GV115 vector and transfected into the packaging cells 293T to produce lentivirus particles.The particles were collected and transfected into 5637 bladder cancer after titer determination. The experimental group transfected MEX3A-shRNA lentivirus, and the control group transfected negative control lentivirus. Knock down efficiency of MEX3A gene was detected by Real-time PCR.Three days after lentiviral transfection, cell growth was measured by cell count for five consecutive days using the Celigo. Five days after lentiviral transfection, Annexin V staining was performed and apoptosis was detected by flow cytometry. Results The MEX3A-shRNA lentiviral vector was successfully constructed and a bladder cancer cell line that MEX3A gene stably suppressed was established. The knockout efficiency of MEX3A gene reached 74%. Celigo cell count detection showed that the proliferation rate of the experimental group 5637 cells was significantly inhibited compared with the control group. Flow cytometry showed that the apoptosis of 5637 cells increased significantly in the experimental group. Conclusion MEX3A gene can promote the proliferation of bladder cancer cells and inhibit the apoptosis of bladder cancer cells.