Abstract: In order to understand the photosynthetic physiological adaptability,diurnal courses of net photosynthetic rate (Pn),light response curves and CO2 response curves of 2 grapevine cultivars (Vitis vinifera L.and Vitis vinifera L.) were measured by Li-6400 portable photosynthetic system.The results showed that:① The diurnal course of Pn of V.vinifera L.presented a double peak curve with an evidently midday depression in July and August,a single peak curve in June was also observed.By contrast,diurnal course of Pn of V.vinifera L.manifested single peak curve during the whole experimental period.② except for July,the stomatal conductance (Gs),evaporation rate (E) and water use efficiency (EUE) were significantly higher than that of V.vinifera L..③ V.vinifera L.had a higher apparent quantum yield (AQY),whilst Vitis vinifera L.had a higher light saturation point (LSP),light compensation point (LCP),maximum photosynthetic rate (Pnmax) and dark respiration rate (Rd).④ Compare with V.vinifera L.,V.vinifera L.possessed a higher photosynthetic capacity (Amax),CO2 saturation point (CSP),maximum carboxylation rate (Vcmax),maximum electron transportation rate (Jmax) and photorespiration rate (Rp).Base on those observations,we postulated that the V.vinifera L.has a better adaptability and photosynthetic ability than that of V.vinifera L.,which probably indicate its high yield.