Abstract: In order to study the influence of microstructure heterogeneity of titanium alloy on hydrogen diffusion and mechanical properties, a polycrystalline microstructure model is established. The random grains are generated by the Voronoi diagram subdivision principle, and the influences of the microstructural mechanical properties and hydrogen diffusion on the loading load, grain orientation, grain size and material are analyzed. The results show that the load can promote the hydrogen diffusion and has no effect on the stress concentration. The crystal orientation is the main reason for the uneven stress distribution in the microstructure, and the larger the grain size, the more serious the stress concentration. Under the same load, the stress concentration in the β-titanium alloy is more obvious than that in the α-titanium alloy, and the hydrogen is more easily enriched in the β-titanium alloy.