The nascent crystals of a bisamide β nucleating agent with different morphologies were successfully prepared by a method of antisolvent precipitation. The typical crystallites, cuboid and rectangular single crystals were obtained by using the antisolvents of H2O, DMF and C2H5OH, respectively. Furthermore, the influences of these as-prepared nucleating agents (NAs) on the crystallization behaviors of polypropylene including homopolymer (iPP) and copolymer (IPC) were investigated in detail. It is found that the crystallites (NA-H2O) quickly induce the nucleation of polypropylene (PP) while the large rectangular single crystal (NA-C2H5OH) show inferior β-nucleating ability to PP. Particularly for IPC system, an inhibited nucleation phenomenon can be ascribed to the competition between potential α-nucleator which is brought about by unique compositions and phase construction and β-nucleators we added. In the isothermal crystallization of iPP and IPC systems, the upper critical temperature for growth transition from β phase to α phase is correlated with the morphology and size of nucleators, and this result has never been reported before. And, the upper critical temperature for growth transition is enhanced due to addition of NA-H2O in iPP and especially in IPC. Compared to iPP system, the crystallization does not follow three-dimensional and spherocrystal growth pattern in IPC system, and this might be resulted from its complex component and structure. Furthermore, the plateau of Tmα1 as a function of Tc exhibited in iPP system still need to be further investigated.