Field-growing maize seedling was transplanted onto measuring board with soil reserved. Images of plant were captured with calibrated binocular stereovision system. The binary images were extracted and segmented into leaves and stems according to phyllotaxis. An algorithm of Douglas-Peucker polygonal approximation of leaf contour was applied to find matching points of two corresponding images. Projecting 3-D points of maize seedling onto plant plane and plant horizontal plane, fitting and interpolating the projected points to generate leaf curve so that the leaf length, leaf insertion height, azimuth and inclination angle could be calculated.