In order to explore the microbial mineralization reaction process and influencing factors in the seawater environment, this paper adopted the method of Microbially Induced Carbonate Precipitation (MICP) aqueous solution experiment was carried out by changing the concentration of nutrient salts, the volume ratio of bacterial solution to nutrient salts and environmental temperature. Then, SEM, XRD and EDS tests were used to detect the aqueous solution products, and the mechanism of MICP reaction in seawater environment was speculated. The results showed that :(1) under different water environment conditions, when the nutrient concentration was 1mol/L and the volume ratio of bacterial liquid to nutrient was 30:120, the reaction rate was the fastest and the sediment produced was the largest; (2) The effect of temperature on the precipitation reaction of calcium carbonate is obvious. The reaction rate at room temperature (25℃) is higher than that at low temperature (4℃), and the reaction is fully carried out. (3) In seawater aqueous solution test, high pH value can accelerate the reaction, and the presence of Mg2+, Ba2+ plasma in seawater makes the precipitate contain a small amount of basic magnesium carbonate (Mg5(CO3)4(OH)2·4H2O), BaCO3 and other mineral components in addition to CaCO3. The results of this study can provide theoretical support for MICP method to reinforce calc-sand subgrade in south China Sea island engineering.