Abstract: In order to study the effect of Humic acid water-soluble fertilizer on wheat photosynthetic characteristics and yield under water stress. Pot experiment were carried out to study the effect of Humic acid water-soluble fertilizer on wheat (‘Yongliang4’) chlorophyll content, photosynthetic rate, stomatal conductance，transpiration rate，yield under water stress after jointing stage. The results indicated that, photosynthetic characteristics on wheat were improved by plant growth regulator under different water stress, compared with control, chlorophyll content and photosynthetic rate increased by 5.62%-84.32% and 0.87%-75.38%, stomatal conductance and transpiration rate decreased by 7.96%-53.25% and 15.96%-58.32%. Net photosynthetic rate and chlorophyll content were decreased after water stress. The function of spraying plant growth regulator could increase chlorophyll content and net photosynthetic rate, and decrease transpiration rate under water stress. As a result, wheat could enhance water use efficiency. The yield was improved by 4.48%-7.75%, and the yield increased order was normal water supply > moderate water stress > mild water control. The analytic results showed that plant growth regulator could improve photosynthetic characteristics and increase yield on wheat.