The present disclosure relates to a method and device for estimating a point spread function. In one implementation, a method includes capturing, by a scanning device, an image by scanning a plurality of rectangle blocks which are same sized and closely arranged, wherein the plurality of rectangle blocks are made of different materials and/or have different mass thicknesses, and an incident direction of rays is perpendicular to a scanning direction and a surface of the plurality of rectangle blocks arranged closely during scanning; obtaining line spread functions for two directions along a length side and a width side of each of the rectangle blocks based on the scanned image, and obtaining standard deviation parameters of the line spread functions; and combining the standard deviation parameters for the two directions to obtain a two dimensional Point Spread Function (PSF) parameter so as to estimate the point spread function.