Abstract: Under the global energy transition context, hydrogen energy, as a clean energy carrier, has become pivotal for future development. However, its storage and transportation challenges significantly constrain the advancement of the hydrogen industry. Ti-Mn-based AB₂-type Laves phase hydrogen storage alloys have garnered considerable attention due to their high hydrogen storage density, low cost, and favorable kinetic properties. Nevertheless, their practical application is hindered by issues such as high hydrogen absorption/desorption plateau pressures and pronounced hysteresis. Annealing treatment, as an effective approach for optimizing alloy performance, requires further investigation regarding its mechanism of influence on the hydrogen storage properties of Ti-Mn-based alloys. This study systematically examines the effects of different annealing temperatures on the microstructure and hydrogen storage performance of Ti_0.85Zr_0.15Mn_1.4Cr_0.1V_0.2 alloy. Through comprehensive analyses including XRD, SEM, EDS, PCT testing, and kinetic evaluations, the following findings were obtained: Annealing treatment maintained the primary C14 Laves phase structure of the alloy but significantly influenced lattice parameters and microstrain. With increasing annealing temperature, lattice constants and unit cell volume expanded. Notably, the alloy annealed at 950 ℃ for 10 h exhibited the maximum full width at half maximum （FWHM） value and minimal lattice strain. Regarding hydrogen storage performance, annealing treatment slightly reduced activation capability, with prolonged incubation time for initial activation observed athigher annealing temperatures. Compared to the as-cast alloy, the annealing treatment significantly reduces the inclination of the PCT curve, improves the effective hydrogen release and enhances the cycle life. The alloy annealed at 950 ℃ for 10 h has the best overall performance. Compared with the unannealed cast alloy, the hydrogen storage capacity is slightly reduced from 1.816% to 1.802%, but the slope of the plateau is reduced from 1.537 to 0.953, and the effective hydrogen release at 0.1 MPa is enhanced from 1.348% to 1.444%, and the capacity is maintained at 99.7% after 100 hydrogen suction/discharge cycles. retention rate of 99.7% after 100 cycles of hydrogen absorption and release. The 950 ℃ annealing condition achieved optimal balance between lattice regulation and performance enhancement.