The application relates to the material field and relates to a preparation method of a polyurethane microporous elastomer, which comprises the following steps: step 1, heating a mold to 90 DEG C + / - 5 DEG C, and injecting a component a into the mold; step 2, keeping the mold temperature, and injecting a component b into the mold; step 3, rotating the mold to mix the component a and the component b in the mold, heating the mold to 110 DEG C + / - 5 DEG C, and continuously rotating the mold to make the mixture react and solidify to form a product, and the product is aged and demolded to obtain the polyurethane microporous elastomer. The application can guarantee the performance of the finally obtained polyurethane microporous elastomer.