The invention provides a calcium carbonate, rubber and polyvinyl chloride composition and a preparation method thereof; the composition comprises the following components by weight: 100 parts of initial composition of calcium carbonate and rubber, and 50-200 parts of polyvinyl chloride. The preparation process of the invention is simple; the cost is greatly reduced; the impurities in the product are less; polyvinyl chloride particles are used as a physical isolating agent, which solves the problem of bonding of the initial composition during drying; the drying process is simple and practical, avoids the pollution and energy consumption of large drying equipment; the cost is effectively controlled; the composition of the invention is applicable to polyvinyl chloride toughening modification, can increase the impact strength of polyvinyl chloride from 3.7 kJ/m2 to 48 kJ/m2 while the tensile strength and flexural modulus are almost maintained constant.