In this paper, the studies on the petrology, diagenesis and diagenetic facies are conducted for Silurian Kepingtage Formation sandstone reservoirs in Tarim Basin. The reservoirs are mainly composed of lithie quartzose sandstone, arkose quartzose sandstone, litharenite, feldspathic litharenite. The diageneses mainly include compaction, cementation, replacement and dissolution. Among them, the later takes the dissolution of early-period carbonate cements as main form, the generated secondary pores and fissures can obviously improve the physical properties of the reservoirs, but the compaction and later-period carbonate cementation result in the losses of primary and secondary pores and fissures. Four kinds of main diagenetic facieses are recognized.