The invention discloses a method for preparing a polypropylene/hydrotalcite nanometer composite material by using hydrotalcite as a nucleating agent, and belongs to the technical field of polymer/inorganic nanometer composite material preparation. According to the method, the prepared hydrotalcite is washed by acetone and is then dispersed into xylene; next, the materials are added into the molten polypropylene xylene solution; stirring is performed; through ethanol extraction, the polypropylene/hydrotalcite nanometer composite material is obtained. The method has the advantages that the hydrotalcite which is not dried is directly added into the polypropylene solution; the agglomeration of the powder body hydrotalcite in polypropylene substrates can be avoided; the polarity is reduced by the hydrotalcite washed by the acetone; the compatibility of the hydrotalcite and the nonpolar polypropylene is improved, so that the dispersibility of the hydrotalcite in the polypropylene is better. The high-dispersibility hydrotalcite achieves the heterogeneous nucleation effect in the polypropylene crystallization process; the effects of inducing the polypropylene crystallization and accelerating the crystallization speed are achieved.