Abstract: The effect of stress triaxiality on the fracture strain of AZ31 magnesium alloy was analyzed by the combination of experiment and finite element numerical simulation.Quasi-static tensile tests were performed on smooth samples and three groups of samples with different notch radius at a tensile speed of 0.5 mm/min.Then, three sets of sample data were selected to establish a model of the effect of stress triaxiality on fracture strain of AZ31 magnesium alloy at room temperature. The established damage model was substituted into ABAQUS finite element software for simulation. The simulation results are basically consistent with the rest of the experimental results, which can verify the correctness of the model.