The wettability of minerals constrains the characteristics of micro-flow and distribution of fluids in reservoirs. The difference of wettability between oil and water lead to different types fluid inclusions formed in reservoirs. Experimental analysis of mineral surfaces show that quartz is distinct oleophilic, but the wettability of calcite is no obvious difference between water and crude oil. Gasoline extend completely on quartz and calcite, it means that all minerals are oleophilic for light oil. Experiments of synthetic hydrocarbon-bearing inclusions and analysis of fluid inclusions from natural reservoir indicate that wettability have great effect on forming of fluid inclusions and in reservoir. Results of experiments proved that it have significantly effect on mineral crystal growth, diagenesis be suppressed, and the number of hydrocarbon-bearing inclusions decrease during accumulation of light oil. However, it does not remarkable effect on diagensis and forming of inclusions during emplacing of heavy oil. Overall, oils restrain quartz much more than calcite during accumulation of oil and gas because quartz is more oleophilic than calcite. So, it is always more hydrocarbon-bearing inclusions in calcite than quartz in same reservoir.