Microstructure and room-temperature mechanical property of TC21 titanium alloy treated by continuous multistep hydrogenation at different temperatures were studied by OM, XRD, TEM and compressive test. Results showed that the size of α phase decreased obviously and β phase became the main phase when the hydrogenation temperature exceeded 1073 K. The content of δ hydride increased first and then decreased gradually with the increase of hydrogenation temperature. The strain softening phenomenon appeared during the compression process of TC21 titanium alloy when the hydrogenation temperature exceeded 1073 K and became obvious with the increase of hydrogenation temperature. The ultimate compression of TC21 titanium alloy decreased first and then increased with the increase of hydrogenation temperature, and increased by 67.51% compared with that of the as-received TC21 titanium alloy when the hydrogenation temperature was 1123 K.