In this work, Zn/ZnO composite photocatalyst was successfully synthesized by simple hydrothermal method. Photocurrent test shows that the presence of Zn can effectively improve the light response of composites. Electrochemical impedance spectroscopy indicates that Zn/ZnO has higher point and separation efficiency and faster carrier transmission. Degradation tests of methyl orange showed that Zn/ZnO had higher degradation efficiency than commercial ZnO. In the same time, Zn/ZnO can degrade nearly 90% of methyl orange, while commercial zinc oxide has less than 10%. Meanwhile, the photocatalyst synthesized in the test of photocatalytic removal of NO also shows higher photocatalytic activity. Compared with commercial ZnO, which removed 48% of NO in 20 min, Zn/ZnO could remove 74% of NO in 8 min, and NO will be further oxidized to NO3- after being oxidized to NO2, which can effectively reduce secondary pollution in the reaction process. These results indicate that Zn/ZnO composite photocatalysts have high photocatalytic activity in both solid-liquid and gas-solid systems. Graphic Photodegradation of MO (a), and NO removal (b) photocatalytic mechanism of Zn/ZnO under irradiation.