A new kind of polyamide-6,6/mobile crystalline material (PA66/MCM-41) hybrid composites were prepared by in situ polymerization. The crystal structural and physical properties of these composites were investigated by Fourier transform infrared and nitrogen adsorption/desorption measurements. The nonisothermal crystallization behavior of PA66/MCM-41 was studied through differential scanning calorimetry measurements. Ozawa, Mo, and Kissinger models were used to analyze the kinetics of the nonisothermal crystallization process. It was found that MCM-41 acting as a nucleating agent in composites accelerated the crystallization rate; the Ozawa method failed to describe the nonisothermal crystallization behavior of PA66/MCM-41 composites. However, the Mo model was able to describe the nonisothermal crystallization process fairly well.