Abstract: Using split plot design, a field experiment was conducted in an irrigated desert soil in Hexi oasis to investigate the effect of water and fertilizer coupling on yield and physiological characteristics such as net photochemical efficiency (ΦPSⅡ), photochemical quantum yield (Fv'/Fm'), coefficient of photochemical quenching (qP), non photochemical quenching coefficient (qN) and photo inhibitionin by using Baby Cabbage variety ‘Chunyuehuang’. The results showed that Pn, Ci, Tr and Gs values of baby Cabbage under the condition of 75%~90% field water capacity plus soil fertilizer combination of N 350 kg·hm^-2+P₂O₅ 400 kg·hm^-2+K 300 kg·hm^-2 were significantly higher than any other treatment at the early, middle and late stage of leaf lotus throne. This indicates that Baby Cabbage plants maintain higher physiological activities under this condition. The dynamics of Pn, Ci, Tr and Gs of Baby Cabbage was in the order of middle lotus throne > late lotus throne > early lotus throne.