Abstract: The Coherent Gradient Sensing (CGS) technology is introduced briefly. The drawback of original CGS is presented. Then the modified CGS is proposed. The optical set-up of this method is the same as the original CGS. It needs only several (greater than two) CGS interference images under different loadings, and can accurately obtain the fringe order of random position in the CGS interference image. This method needs neither additional optical set-up nor complicated image processing techniques. At last, static mode I fracture experiments in three-point bending specimen are carried out using the modified CGS method, and the stress intensity factor is obtained. The experimental results show that the modified method can evidently reduce the error from the process of extracting the fringe order, and improve the precision of the CGS method.