In this work, octamethylenedicarboxylic dibenzoylhydrazide (TMC-300) was used as a highly efficient -phase nucleating agent for isotactic polypropylene (iPP) for the first time. The influences of TMC-300 on crystallization and melting behaviors as well as mechanical and thermal properties of iPP were analyzed by differential scanning calorimeter, polarizing optical microscope, wide-angle X-ray diffractometer, and universal mechanical tests. The results reflected that TMC-300 had excellent nucleation effect and that 0.20wt% was the optimal addition concentration for iPP. Compared to those of neat iPP, the crystallization temperature, the bending modulus, and the heat distortion temperature of nucleated iPP was increased by 7.10 degrees C, 14.3% and 18.30 degrees C, respectively, at 0.2wt% addition amount of TMC-300. In addition, the spherulite size of iPP after addition of TMC-300 was also reduced obviously.