The crystalline structure, morphology, and nonisothermal crystallization and melting behavior of isotactic polypropylene (iPP) with and without a novel nucleating agent containing amide group (TMC-328) were investigated with differential scanning calorimetric (DSC), polarized optical microscopy (POM) and X-ray diffraction (XRD). TMC-328 could increase the crystallization temperature and accelerate the crystallization rate of iPP. As an efficient α-form nucleating agent, the addition of TMC-328 could obviously reduce the spherulite size of iPP. There is a critical concentration of TMC-328. When the content of TMC-328 is 0.1%, iPP matrix exhibits the maximum crystallization peak temperature (123 °C) and the maximum crystallinity of 45.0%. With the content of TMC-328 increasing, crystallinity of iPP matrix decreases obviously. XRD measurements indicate that the crystal structure of the α-form of iPP is unaffected by TMC-328.