Abstract: The standard curve of the lower leg cross section which located at the top part of men’s socks is critical for optimal design of sock products. In this paper, 6cm above the medial side of ankle bone was scanned and the right leg cross section images could be intercepted using the software. All lower leg cross-section curve images were stored and each 5 degree interval was segmented in a plane rectangular coordinate system. Using Matlab software, a 72-point coordinate value was determined, average x values and y values of the 72 points coordinate, an average shape of the cross-section was obtained. The quadratic equation of standard curve of the lower leg cross section can be obtained using fitting curves by SPSS software, the building of equations provided basic data for mathematical model of pressure. Meanwhile, we calculated the perimeter of the standard curve, these solutions supply a theoretical reference for optimal design the initial girth of top part of men’s socks and the selection of fabric elastic elongation.