N,N'-Dicyclohexyl-2,6-naphthalenedicarboxamide (NU100), a commercial β-nucleating agent (NA) for isotactic polypropylene (iPP), is found dissolvable in iPP melt. Various heating temperatures (T _hs) of iPP/NU100 cause different solubilities of NA, resulting in various aggregation morphologies of NU100 in the melt. Moreover, nucleation efficiency of NA NU100 on iPP changes with the T _h of iPP/NU100. In this article, the effects of T _h on nucleation behaviors of iPP nucleated with different concentrations of NU100 were systematically studied. The results indicated nucleation efficiency of NU100 depended not only on concentration of NA but also on T _h of nucleated iPP. With the increase of T _h, crystallization peak temperature (T _cp) of nucleated iPP decreased remarkably. The whole process that T _cp shifted from 126.8°C to 120.8°C was obtained by investigating the nucleation behavior of iPP/0.1 wt% NU100. Polarized optical microscopy observation confirmed lower T _cp, representing the crystallization of iPP nucleated by dissolved–recrystallized NA NU100. Further, diverse aggregation morphologies of NA in iPP melt during crystallization were observed. A schematic diagram was proposed illustrating the morphologies formed during recrystallization process of NU100 melted at different T _hs.