Abstract: The effects of deficit irrigation on water use efficiency and fruit quality of six years old pear-jujube tree were studied. Treatments included pear-jujube trees growing in sufficient water supply during the whole growing period (T1), low water deficit during the flowering-fruit bearing stage (T2), moderate water deficit during the fruit spreading growth stage (T3) and serious water deficit during the fruit maturing stage (T4). Experimental results indicate that the trend of the potential evaportranspiration (ET₀) in greenhouse is the same with that out of greenhouse, the inside ET₀ is larger than that of outside, and the relationship between inside ET₀ and outside ET₀ is very remarkably linear, R² is 0.9501. The soil moisture consumption rates were reduced for all treatments during water deficit stages, the leaf photosynthesis and the transpiration rate were decreased simultaneously. The leaf WUE was advanced for the light water deficit during flowering-bearing fruit and the serious water deficit during fruit maturing, but it was reduced for the middle water deficit during fruit speedy growth. The treatment of non-irrigation during fruit maturing had a little infulunce on average fruit weight, Vitamin C content and soluble albumen, but enhanced the organic acid content and soluble solid matter, advances the fruit quality. Therfore the yield was infulunced hardly for serious water deficit during fruit maturing, the leaf WUE was enhanced during the water deficit stage and the fruit quality was improved.