The invention discloses a surface treatment method of nano-calcium carbonate used for polyvinyl chloride plastisol. The surface treatment method comprises the following steps: adding nano-calcium carbonate serous fluid into a reaction kettle, wherein the specific surface area (BET) of nano-calcium carbonate in the serous fluid is 18.0-60.0m<2> / g and the pH of the nano-calcium carbonate serous fluid is 8.5-9.5; heating to 70-95 DEG C, stirring, adding a mixed modifier accounting for 1.8-6.0% of the mass of the nano-calcium carbonate in the serous fluid, continuing stirring for 30-180 minutes, thus completing surface treatment. The mixed modifier is a mixture of stearic acid alkali metal saponified matter and calcium stearate, the mass ratio of fatty acid to calcium stearate in the complex modifier is 20-70%, and the proportion of the using quantity of the fatty acid to a saponifier is 1: 1. According to the method, the fatty acid is saponified by a strong base, so that the shortcoming that the fatty acid is difficult to react with the surface of calcium carbonate in water to generate the calcium stearate during wet process surface modification of the nano-calcium carbonate can be overcome; and the calcium stearate is directly introduced through fatty acid saponification liquor, so that a significant surface modification effect is obtained. The method has the advantages that raw materials are low in price and easy to obtain, the processes are simple and feasible, and the quality of a product is state. The method has significant economic benefits and social benefits.