Abstract: Effects of phosphate nucleating agents, carboxylate nucleating agents, rosin type nucleating agents and sorbitol type nucleating agents on crystallization behavior of isotactic polypropylene (i-PP) were investigated by Fouriertransform infrared spectroscopy, powder X-ray diffraction, differential scanning calorimetry and polarizing light microscopy. The results indicated that the crystallization kinetics of i-PP was significantly influenced by its crystallization rate, crystallization temperature and crystallinity because of the difference in the structure of nucleating agents. Among these nucleating agents, the phosphate nucleating agents exhibit the shortest half time for the crystallization of i-PP, and its crystallization temperature was up to 129.8 ℃.