The invention discloses a method for detecting wave aberration of a projection type photo-etching machine imaging system. The method comprises the following steps: establishing a quick positive model of the photo-etching machine imaging system, analyzing and resolving a Zernike coefficient sensitivity matrix, optimizing and resolving a detection mask pattern and resolving the wave aberration measured on the basis of a single light intensity. Through the method, the wave aberration measured on the basis of a single defocus space image light intensity can be detected by analyzing and resolving a space image light intensity value and the Zernike coefficient sensitivity matrix without the aberration.