Abstract: A new method depending on weighed least square was proposed, aiming at the shortcomings of the existing interferogram calibration method. It used the edge information differences between standard parts edges and fringes edges, then extracted the target edges by using appropriate mask, and finally used the weighed least square way to position the edge more exactly. The new method can figure out the real length of each pixel finally depending on the standard parts known size. The experiments show that this method costs half time than Hough transform, and the positioning accuracy is less than 1 pixel. It can calibrate each type of interferogram well with strong practicability.