Photosynthetic characteristics of net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), intercellular CO2 value, light compensation point (LCP), light saturation point (LSP), photosynthetic potential of Zayoudou No. 1 and its parents (W931A and WR016) were measured. The results showed that net photosynthetic rate of Zayoudou No. 1 and its parents were single peak curves. Net photosynthetic rate of Zayoudou No.1 at 8:00 was significantly higher than that of its parents. Zayoudou No.1 had lower light compensation point and higher light saturation point than its parents, which could make strong ability of weak light. Through analyzing the group of photosynthetic potential, leaf area index and photosynthetic potential were significantly higher than W931A and WR016 in flowering stage, podding stage and drum grain stage. Leaf area index and photosynthetic potential of Zayoudou No.1 and tis parents showed a rising trend from flowering stage to podding stage, from podding stage to drum grain stage. The conclusion showed that Zayoudou No.1 having strong utilization ability of weak light and higher leaf area index and photosynthetic potential, which were beneficial to the improvement of yield.