Abstract: The authors analyze the influence of diagenesis and diagenesis types on physical properties, and relationships between diagenesis and distribution pattern of oil and gas in the Xiashihezi Formation in Linxing area though observing lots of rock slice, scanning electron microscope and cathodoluminescence. Diagenesis types include compaction, cementation and weak dissolution; Compaction greatly destroys primary pore volume, cementation blocks pores and throats, dissolution improves the reservoir quality of the sandstones in the Xiashihezi formation. The condition of forming lithologic trap are the diagenesis differences in different part of the sand, in the vertical of which, the bottom and top of subsea distributary channel and the mouth bar faces are low permeable and the middle are permeable formation, hence, subsea distributary channel and the mouth bar faces sands can make a lithilogic trap; In the plane, the primary pore and the secondary pore facies, the secondary pore facies spread over subsea distributary channel and mouth bar facies, which have preferable sorting and rough granularity. sand with higher matrix are impermeable to keep oil and gas out the plane area in the far bar and sheet sand faces with worse sorting and thinner granularitymainly. The sandstone with higher matrix in distal bar and sheet sand microfacies, which have worse sorting and thinner granularity, are hypotonic, it's keeping oil and gas out the plane area. As a whole, reservoir with subsea distributary channel and mouth bar microfacies, meanwhile, the primary pore and the secondary pore facies, or the secondary pore is the beneficial sites for hydrocarbon accumulation, then, gas-bearing properties of reservoirs with distal bar and sheet sand microfacies, meanwhile, authigenic kaolinite inter grain pores diagenetic facies or cementation and weak dissolution facies, are poor.