The work aims to improve the corrosion resistance of TA2 in oxalic acid solution, reveal the mechanism of hydrogen charging to improve the corrosion resistance of titanium in oxalic acid solution. The surface of TA2 was hydrogenated by hydrogen charging. The effects of hydrogen charging on the surface morphology and phase composition of the sample were analyzed by SEM and XRD. Electrochemical tests and corrosion immersion experiments were carried out to study the corrosion resistance of TA2 samples with different hydrogen charging times in oxalic acid solution. After hydrogen charging, a layer of titanium hydride with TiH1.5 as the main component was formed on the surface of the TA2 sample. The thickness of the titanium hydride layer was thickened with the extension of hydrogen charging time. Electrochemical test results showed that with the extension of hydrogen charging time, the self-corrosion potential of TA2 sample in oxalic acid solution gradually increased from –0.7 V (vs. SCE) to about 0 V, and the corrosion tendency decreased remarkably; the polarization resistance Rp gradually increased from 0.2 kΩ?cm2 to 24.1 kΩ?cm2, and corrosion resistance was enhanced. The results of corrosion immersion experiments showed that the corrosion degree of TA2 sample in oxalic acid solution gradually decreased with the extension of hydrogen charging time, and the corrosion rate also gradually decreased from 4.63 mm/a to 0.03 mm/a. In the oxalic acid solution, the titanium hydride layer formed on the surface of the TA2 sample after hydrogen charging has protective effect on the titanium substrate, and the protective effect is enhanced with the thickening of the titanium hydride layer. The protective effect of titanium hydride layer of sample surface on titanium substrate on is related to its structure in addition to its composition: the complete and dense titanium hydride layer can protect the titanium substrate well; while the loose porous titanium hydride not only cannot protect it, but also promotes the corrosion of titanium substrate.