Zinc oxide thin films were deposited on polyethylene terephthalate (PET) substrate by the electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) method at room temperature with the addition of hydrogen to the reaction gas. Diethyl zinc (DEZn) as the source precursor, O-2 as oxidizer and argon as carrier gas were used for the preparation of ZnO film. Scanning electron micrography and X-ray diffraction analyses revealed that the ZnO grains with size of ca. 20 nm had an elliptic cylindrical configuration and were highly c-axis-oriented. The hydrogen content strongly affected the crystallographic structure, electrical property, and composition, as well as the surface roughness of the zinc oxide films. The chemical composition and surface states of the films were further examined by RBS and XPS to find the reason for the different electrical resistivity with variation of H-2/Ar ratio. It can be concluded that hydrogen content plays an important role in increasing the Hall mobility, hole concentration, and electron concentration in our experimental range.