A new method of sub-pixel localization based on SUSAN and Hough transform was presented. The size of template selection was proposed and the straight edge response was defined in SUSAN algorithm. Meanwhile, weighted Hough transform was conducted. First, the straight edge response was used to extract edge. Then, the Hough transform was computed only when edge points of line had the value of the response and the value was added in an accumulator as a weight. The local areas of parameter space were divided for the second Hough transform and the edge detection was attained by point fitting as sub-pixel localization position. Experimental results show that the sub-pixel localization precision of the method can reach 0.3 pixels. It has greatly decreased calculation compared with traditional edge detection and Hough transform. The method is simple and has better properties of anti-noise capability and robustness. Meanwhile, it provides a new way for sub-pixel localization of analytic curve.