Using LI-6400XT portable photosynthetic measurement system, the diurnal variation process and their correlation of physiological factors such as Pn, Gs and Tr of Zhenzhuyouxing apricot planted in sandy wastelands in the middle reaches of Heihe River were studied. The results showed that the diurnal variation of Pn in the leaves of Zhenzhuyouxing apricot presented a bimodal curve, and there was an obvious photosynthetic "siesta" phenomenon.Gs also showed a bimodal curve. There was a negative correlation between WUE and Tr. The factors affecting photosynthesis include both stomatal and non-stomatal restriction.