In this letter a new synthetic strategy has been established for MoO3 nanobelts by oxidizing Mo powders with H2O2 in neutral water at 70 degrees C and a subsequent hydrothermal treatment at 140 degrees C. By introducing alcohol into this system, we can selectively prepare blue HxMoO3 nanobelts. The photoluminescence (PL) property can be greatly altered before and after hydrogen incorporation into MoO3 nanobelts. The mechanism on formation process of nanobelts has also been addressed.