Abstract: The diurnal variation of photosynthetic fluorescence characteristic parameters and fruit setting of mature jujube（Ziziphus jujuba Mill.cv.‘Huizao’） leaves with different canopy layers were studied, in order to construct the high light efficiency planting mode and tree structure of dense planting jujube garden in southern Xinjiang.The results showed that the diurnal variation curves of net photosynthetic rate（Pn） in different canopy showed a ‘bimodal’ curve, and the diurnal mean value of Pn showed that canopy Ⅰ＜canopy Ⅱ＜canopy Ⅲ,the diurnal variation of stomatal conductance（Gs） was similar to that of Pn, but the time of Gs reaching the peak was different in different canopy.The intercellular CO₂ concentration（Ci） showed a ‘parabola’ shape, from the overall change of the curve, the daily change trend of Ci of leaves in different canopy layers showed that canopy Ⅰ＞canopy Ⅱ＞canopy Ⅲ,while the daily change curve of stomatal limit（Ls） of leaves in different canopy layers was just opposite.From the whole water use efficiency（WUE） change curve, canopy Ⅲ＞canopy Ⅱ＞canopy Ⅰ.The chlorophyll fluorescence parameters in different canopy layers were different, the upper leaves showed higher advantages in light inhibition, the middle layer and the lower layer were the weakest.The fruit setting in different canopy layers was significantly different（P＜0.01）.The fruit hanging rates of canopy Ⅰ,Ⅱ,Ⅲ were 0.39,0.53 and 0.99 fruit per fruiting shoot, respectively.In order to improve the quality of jujube fruit, densely planted jujube orchard in Southern Xinjiang should adopt reasonable measures to improve the overall light transmittance of jujube orchard, as well as pruning from top to bottom and thinning branches in the inner chamber to keep enough light flux.