The invention discloses a photosensitive unit, an array substrate of a display panel and a manufacturing method of the array substrate. According to the photosensitive unit, photovoltaic conversion is conducted with a P type doping region/ intrinsic region/ N type doping region structure, light currents generated do not change dramatically easily due to the fluctuation of the working voltage, and the degree of accuracy is high; furthermore, due to the fact that the P type doping region/ intrinsic region/ N type doping region structure is arranged longitudinally preferably, the length, width and height of the intrinsic region can be set more flexibly when the photosensitive unit is assembled on the array substrate of the display panel, the optical sensing area of the photosensitive unit is enlarged as much as possible, photovoltaic conversion capacity is improved, and as a result, the array substrate of the display panel comprising the photosensitive unit and the display panel are higher in ambient light sensing capacity, reliability and sensitivity. The photosensitive unit, the array substrate of the display panel and the manufacturing method of the array substrate are suitable for various display panels.