Abstract: In order to offer scientific base for the cultivation of Parthenocissus quinquefolia planch in the barren mountain area, with CIRAS^-2 portable photosynthesis system which is made in PPS corporation of England, the photosynthesis （P_n） and transpiration （T_r） responses of Parthenocissus quinquefolia planch two years old leaf to light intensity under different soil moisture conditions were studied. The results indicated that the photosynthesis, transpiration and water use efficiency （E） of Parthenocissus quinquefolia planch leaf has notable threshold responses value to the level of soil moisture and the variation of photosynthetic active radiation （R_p）. Parthenocissus quinquefolia planch's Pn is at a relatively high-level when the volumetric water content （W_v） is about 12.6%^-20.7%, relative water content （W_r） is about 45.2%-74.3%. When Wv is about 18.3%, the Pn and Tr reach the highest value while the E is relatively low. When the Wv is about 12.6% （W_r is about 45.2%）, the E reaches the highest level. The fitting soil moisture range which can keep Pn and E at relatively high-level is 12.6%^-18.3%for W_v and 45.2%-65.7% for W_r. Out of this range, Pn and E will descend obviously. In the fitting range of Wv, the Pn and E maintain a high-level when the Rp range is 400^-1000μmol.m ^-2 .s ^-1, otherwise, the E will fall, and the most suitable R_p is 800μmol.m ^-2 .s ^-1 . The results indicated that the Parthenocissus quinquefolia planch can adapt to a wide ange of illumination intensity. It has the property of strong drought-resistance but can not stand the high soil moisture environment. Therefore, it is a suitable liana to the afforestation in barren mountain area.