As the hydrocarbon exploration advances into the deep and ultra-deep reservoirs，it is important to study the development rules of the favorable reservoirs in deep layers. The Xishanyao Formation of Yongjin Oilfield in Junggar Basin has a large burial depth，tight matrix，and it is overpressured. However，the properties of the oil-bearing intervals are favorable，and the overpressured fluid has complex correlation with the evolution of formation properties. Therefore，the attentions are focused on the evolution of key factors such as diagenesis，formation properties，pressure and oil-gas filling and their time-space matching of Xishanyao Formation in Yongjin Oilfield，to study the development mechanism of favorable reservoirs. The results show that the formation of high porosity zone is related to five factors including，low debris content，early overpressure filling，diagenesis inhibition，hydraulic fracturing，and secondary dissolution. The interaction mechanism is that the sand body with the low debris content is weakly compacted，in which the primary pores are well preserved，and the early overpressured hydrocarbon bearing fluid is preferentially injected into the primary high porosity zone to make its compaction delay comparing with sandstone with the high debris content. Due to the inhibition of hydrocarbon fluid filling and chlorite film，the porosity of the high-porosity oil-bearing section has remained basically unchanged，and the hydraulic fracture is formed at the same time by strong overpressure，which further improves the permeability of the reservoir. Depending on the fluid activity space provided by the primary pore and hydraulic fractures，the secondary dissolution pores of theprimaryporeswellpreservedorthefracturedevelopedsectionarewelldeveloped.Thetotalremainingporosityisabout 7%.