This paper discusses about the production and characterization (i.e. morpohology and crystallization behavior) of polypropylene filled nano-CaCO3 composites (i.e. PNCCs). The PNCCs were successfully prepared via melt mixing/compounding process using nano-CaCO3 masterbatch in a twin-screw extruder (TSE) machine. Different nano-CaCO3 concentrations (i.e. 5, 10 and 15 wt%) and two times process (i.e. 1st cycle and 2nd cycle) were used to analyze the influence of nano-CaCO3 concentrations and reprocessing on the morphology and crystallization properties of the PNCCs. The morphology and crystallization properties of the PNCCs were studied using SEM and DSC, respectively. The SEM images exhibited that at low nano-CaCO3 concentration (i.e. 5 wt%), the nano-CaCO3 fillers were well distributed and dispersed in the PP matrix for both NCC-5-I and NCC-5-II samples. Nevertheless, the size of the nanofillers in NCC-5-II sample were smaller than that of the NCC-5-I sample. Additionally, the DSC crystallization thermograms showed that crystallization temperature (Tc) and onset crystallization temperature (Toc) of the PNCCs were higher than the pristine PP. The increases of Tc and Toc for both PNCCs (i.e. 1st cycle and and 2nd cycle) were not much different, which were about 4-5 °C and 3-4 °C, respectively.