Dehydrogenation performances of NaAlH4 doped with transition metal oxides (TiO2, ZrO2, Cr2O3, ZnO) were studied by PCT (Pressure-Content-Temperature), XRD and SEM. The results indicate that the dehydrogenation performances of NaAlH4 doped with TiO2 or ZrO2 are preferable. In addition, the study on different ball-milling methods shows that the ball milling leads to a marked increase of dehydrogenation amount. SEM results show that with prolonging the milling time from 1 to 3 h, the size of the complex became smaller, and these particles were scattered on larger globes. However, those particles would reunite again if the milling time was prolonged from 3 to 6 h. The ball milling does not cause evident structure change, indicating that NaAlH4 has good stability.