The primary pore loss of deep clastic rock reservoir is serious. One of the key problems determining whether deep reservoir can be formed is if secondary pores were developed in the tight reservoir of basin clastic rock. Feldspar dissolution plays an important role in the formation of secondary pores in middle and deep clastic reservoir.Polarized light microscopy, scanning electron microscopy (SEM) and an X- ray powder diffractometer (XRD) were used to characterize the diagenetic features of feldspar at sandstone- shale contacts of delta and related turbidite sandstone bodies in the Shahejie Formation, the central area of Dongying depression. The results show that the acidic pore fluid was generated during thermal maturation of organic matter and the illitization of montmorillonite in the interbedded shales. The results show that the mudstone diagenesis in the sequence of sandstone and mudstone has an important influence on the feldspar dissolution and the formation and distribution of authigenic kaolinite. The effect of sandstone- shale contact on feldspar dissolution is strongly controlled by the geochemical characteristics of organic matter in shale.For turbiditic sandstone bodies with a buried depth of more than 3000 m, due to the expulsion of organic acids from mudstone, the dissolution degree of feldspar alteration is relatively high at sandstone- shale contact, while the kaolinite content is relatively low. The secondary pores thus formed will not be filled with kaolinite, which improves the porosity and permeability of the reservoir at sandstone- shale contacts. However, the delta front sandstone body is shallowly buried, far from the center of the effective hydrocarbon source rock, and lower organic matter content in shale results in less generation of organic acid and lower influence onfeldspar alteration at sandstone- shale contacts. In the sandstone body, especially in the location containing oil and gas, the deep acidic fluid can enter the sandstone body along the migration path of oil and gas before its arrival and cause feldspar dissolution, resulting in relatively high kaolinite content in the oil and gas bearing sandstone body. The research results are of great significance to the formation mechanism of secondary pores in middle and deep sandstone reservoirs, reservoir evaluation and quantitative prediction of reservoir quality.