This paper studies the polycarbonate resin with regrinding ratio and reheating times for the effects of the mechanical properties. The Melt-flow Index (MI) instrument measures the resin’s flow properties. The specimens of tensile and impact were manufactured by injection machine. Finally, to observe the feature of cross section of tensile and impact specimens with scanning electronic microscopic (SEM) and Fourier transform infrared (FTIR). Experiment’s results showed, the Melt-flow Index, MI, which will be increased by highly ratio of regrinding resin. However, reheating-times impacts of MI value are unobvious. Regrinding weakens tensile strength stronger than reheating-times. Regrinding reduces the impact resistance more than tensile strength. Regrinding and reheating-times worsen the closed properties of the specimen’s profile under SEM observation. This is an indication that on Fourier transform infrared spectrometer observing, the regrinding enhancing the transmittances percent but don’t compliance at reheating-times.