Abstract: Related characteristics with photosynthesis were measured using leaves of potato variety Quan-yun No.3 and Quan Yin No.1 SPAD value of variety Quan-yun No.3 were higher than those of Quan Yin No.1.Photosynthetic parameters such as Pn,LSP and LCP in leaves of Quan-yun No.3were higher than those of Quan Yin No.1.AQY of of Quan Yin No.1are higher than those of Quan-yun No.3.Daily change curve of Pn in leaves of Quan-yun No.3showed a single peak and Pn cited bimodal curve of Quan Yin No.1may be related to species characteristics.Daily change curve of Pn were similar to that of Gs in leaves of Quan-yun No.3.It showed that Gs played a major role in the change course of Pn.