By using the gate control characteristics of GaN high electron mobility transistor (HEMT) and the photovoltaic effect mechanism of ferroelectrics, a new type of (photosensitive layer/HEMT) photo-detecting device was prepared. In this paper, mainly studied is the influence of film types and sputtering atmosphere on the photovoltaic performance of light-sensitive films and the light detection ability of the new photosensitive grid detector. The results show that the peak quantum efficiency of the PZT/ZnO composite film reaches 14.55%, and the residual polarization intensity of the PZT film prepared by passing oxygen during sputtering reaches 52.31μC/cm2. The saturation current of the detector deposited with PZT/ZnO composite film under UV light increased by 12.64mA at most compared with that of the dark field source. It can be concluded that the new detector has an excellent ability to detect ultraviolet light, and it provides a new direction for the study of light detection.