To accurately obtain the center point of interference fringes, a method based on interval curve fitting was established. According to the gray value distribution of the interference fringe pattern, we first obtain the R value graph of the interference fringe and perform Gaussian low-pass filtering; then, we remove various noises while retaining the original fringe information. Thereafter, we consider the filtered image as a list of pixel values in the normal direction to obtain a gray distribution curve. Finally, we intercept the image near the peak to perform segmental curve fitting in the increasing interval and the decreasing interval and obtain the intersection point of the two curve fitting functions, which is the center point of the interference fringe. Experimental results show satisfactory curve fitting effect. Compared with the Steger algorithm, the speed of the proposed method is increased nearly ten times. The proposed method can be used to effectively obtain the center point of interference fringes according to the gray distribution law of interference fringes with a simple operation, high precision, and anti-interference characteristics.