The invention discloses a method for detecting a shading part of a photovoltaic cell panel, belonging to the field of photovoltaic power generation. The detection method comprises the following steps of: 1, acquiring an actual image A of a photovoltaic cell array in a photovoltaic cell panel monitoring area; 2, performing gray processing on the actual image A, and comparing the actual image A subjected to gray processing with an original image B, wherein the original image B is a grayscale image in which a shading part does not exist, if the actual image A is the same as the original image B, then the shading part does not exist in the actual image, and then ending the operation, but if the actual image A is different from the original image B, then the shading part exists in the actual image A, and then taking the shading part in the actual image A as a shading area to segment the image. By the method, the shading part of the photovoltaic cell panel is accurately acquired, and the power generation efficiency is improved; and moreover, the using cost is reduced.