Abstract: The effects of different water deficits at different growth stages on stem sap flux of six years old pear-jujube trees in greenhouse were studied. Pear-jujube trees grown in sufficient water supply (T1) and suffered low water deficit (T2), middle water deficit (T3) and serious water deficit (T4) during flowering-bearing fruit, fruit speedy growth and fruit maturing period, respectively. Experimental results illustrated that the weather condition influences stem sap flux in all treatments obviously, visible compensation of stem sap flux in T2 was observed after re-watering, but the compensation was not occurred in T3 and T4. The trends of daily stomatal conductance are uniform with stem sap flux in mass, but the asynchronous phenomena were observed during 12:00 to 14:00 PM and after 16:00 PM. The diurnal changes of stem sap flux were analyzed in all treatments. The multi-relationships among daily stem sap flux of pear-jujube trees and meteorological factors were analyzed for all treatments, the F values are 79.659, 85.321, 104.922 and 94.781 from T1 to T4, respectively, which all are bigger than F_0.95(3,115)=2.69, the R² values are 0.675, 0.690, 0.732 and 0.712 from T1 to T4, respectively. The relationship between the ratio of daily stem sap flux of water deficit treatment and sufficient treatment and relative available soil water content (RAWC) is linear, R² is 0.4489.