Silicon carbide offers distinct advantages in the field of power electronic devices. However, manufacturing processes remain a significant barrier to its widespread adoption. Polycrystalline SiC is less expensive and easier to produce than single crystal. But stabilizing and controlling its performance are critical challenges that must be addressed urgently. Due to its material properties and excellent performance in applications, 3C-SiC is gaining increasing attention in research. This article presents the electrical and material properties of a series of polycrystalline 3C-SiC samples and investigates their interrelationship. The samples were examined using TEM, which confirmed their polycrystalline structure. Combined with XRD and Raman spectroscopy, the grain orientations within the samples were analyzed, and the presence of stress was verified. EBSD was employed to statistically examine the grain structure and size across samples. For samples with similar doping levels, grain size is the most influential factor in determining electrical characteristics. Further EBSD measurements reveal the relationship between resistivity and grain size as log(ρ) = −1.93 + 8.67/d. These findings provide a foundation for the quantitative control and application of polycrystalline 3C-SiC. This work offers theoretical evidence for optimizing the performance tuning of 3C-SiC ceramics and enhancing their effectiveness in electronic applications.