The nucleation of polyoxymethylene (POM) crystallization using attapulgite was studied using differential scanning calorimetry, polarized fight microscopy, wide-angle X-ray diffration and mechanical testing. Two isothermal crystallization kinetic equations were employed to describe the crystallization of virgin POM and POM containing attapulgite as a nucleating agent. The addition of attapulgite decreased the spherulitic size of POM, and interfacial free energies per unit area perpendicular to the molecular chain direction sigma (e) accelerated the crystallization growth rate and enhanced the impact toughness of POM, buts no change occurred for the hexagonal system of POM. The addition of attapulgite up to its saturation concentration in POM increased the number of effective nuclei by three orders of magnitude. A high concentration of attapulgite caused agglomeration of the agent and lowered the number of effective nuclei.