The invention discloses a method for preparing nano calcium carbonate for high-temperature resistant polymers, which comprises the following steps of: purifying, slaking and ageing a limestone calcined product, then adding a crystal nucleus control agent into the generated calcium hydroxide slurry and carbon dioxide mixed gas, carbonizing the mixture to synthesize nano calcium carbonate slurry, heating the nano calcium carbonate slurry, adding a certain amount of fatty acid (salt) modifier into the slurry to perform surface activation treatment, and adding a certain amount of outer heat-resistant modifier emulsion with high heat-resistant group into the slurry to perform heat-resistant wrapping treatment on the surface of the calcium carbonate. The method is reasonable and reliable, is favorable for continuous production operation, and can improve the uniformity of the product and reduce the cost; and the product has the characteristics of high whiteness and low viscosity, and is suitable for polymers of plastic, rubber, adhesive and the like in the fields of automobiles, electronics, spaceflight and the like.