Abstract: In order to explore the diurnal variation of photosynthetic physiological characteristics, the diurnal variation of photosynthesis of different Cornus wilsoniana clones were conducted using the Li-6400 portable photosynthetic system during the flowering stage. The results showed as following: (1) The diurnal variation of net photosynthetic rate (Pn) of G-2、G-3、G-8、G-9 showed double-peak curve, while G-4、G-5、G-6、G-7、G-10、G-11、G-13、G-14、G-15 revealed single-peak one. The daily average of Pn of 12 clones could be divided into 3 categories. It is, G-6、G-7、G-8 for the first category with the maximum daily average of Pn, G-2、G-3、G-4、G-9、G-10、G-11、G-13、G-14、G-15 for the second category with the medium one, and G-5 for the third category with the minimum. (2) Similarly, based on the daily average of Tr, all the 12 clones could be diveded into 3 types too, namely, G-5、G-14、G-15 for low water consumption types, G-13 for medium one, and G-2、G-3、G-6、G-7、G-8、G-9、G-10、G-11 for the highest one. (3) G-8、G-14、G-15 belonged to high water use efficiency types, G-6、G-7、G-11、G-13 to medium one, and G-2、G-3、G-5、G-9、G-10 to low one. The WUE showed a fluctuating tendency, G-5、G-6、G-7、G-8、G-15 belonged to fluctuating clones, while G-9、G-10、G-11、G-13、G-14 showed more stable, and G-2、G-3 were the most stable ones.