The partly enrichment of calcium in sandstone reservoir is one of the important factors affecting the reservoir properties. So the controlling factors and forming mechanism of the enriched calcium is undoubtedly of great significance to the efficient development of the oilfield. In the sandy clastic rocks, calcium enriched with “calcium sharp” in the shape of a top bottom or the mass etc. In this paper, by using physical and chemical methods, the source of calcium, conditions of calcium enrichments and deposition mechanism were analysis. Theresearchresults show that the calcium ions release mainly in the period of syngenetic, supergene and buried lithogenesiswith various acidic water play the part of catalyzing. In the syngenesisand supergenestage, the lake (sea) level falls and the river channel changes, calcium containing compound precipitates through evaporation and chemical reaction equilibrium shift to the left and so does the hypergenesis stage. In addition, the analysis results showed that cause of calcium interlayers are complex including the period of syngenetic, buried diagenesis stage and supergene period by abundant groundwater geochemistry data in eastern block of Sulige gas field.Among them,the buried diagenesisis the most important, and whichwasamain controlling factor.