Abstract: This paper summarized the diagenetic features of C_Ⅰ oil group quartzose sandstone reservoir of Carboniferous system in Tazhong uplift, such as compaction and pressure solution, cementation, dissolution, alteration and replacement.Five stages of diagenesis were classified, including penecontemporaneous, early diagenetic stage A and B, late diagenetic stage A and telo diagenetic stage B.By analysis of the diagenetic mechanisms, furthermore, diagenetic mode is established.For the first time, it is pointed out that the diagenetic environment in this region was a semi-sealed to sealed system. Factors affecting the diagenesis and their relations to reservoir quality of C_Ⅰ oil group are discussed.

Key words: Tarim Basin, Middle, Middle Carboniferous, Sandstone, Diagenesis, Mode, Reservoir, Characteristics