Abstract: Pd/ZnO composites with various palladium mol fractions were prepared through a facile onepot hydrothermal method. Samples were characterized by XRD, HRTEM, EDX and XPS. The results demonstrate that partial Pd are loaded on the surface while the rests are doped in the lattice of ZnO. The change of hydroxyl groups on the surface of Pd/ZnO compounds modified by Pd with various mol fractions was observed by XPS, and the photocatalytic performance of the samples are investigated in detail. It is found that the addition of the palladium chloride solution into the reaction system, can not only increase the amount of the surface hydroxyl groups, but also promote the separation of photogenerated electronhole pairs and thus increase the photodegradation efficiency.