Using nonequilibrium Green's function combined with density functional theory, we investigate the spin-related current generated by the photogalvanic effect (PGE) in monolayer zigzag SiC nanoribbons (ZSiCNRs) by first-principles calculations. Due to its unique atomic structure and band structure properties, we find that 100% spin polarized photocurrent can be easily obtained in a wide range of photon energies by shining linearly/circularly polarized light when ZSiCNRs are in the anti-ferromagnetic (AFM) state. In comparison, when the ZSiCNRs are in the ferromagnetic (FM) state, the spin polarization of photocurrent can vary from 0% to 100% by changing the photon energy or polarization angle. More interestingly, pure spin current can also be generated by changing the circular polarization angle in the FM state. Thus, by properly tuning the photon energy, one can obtain 100% spin polarized current regardless of its magnetic configuration and pure spin current in its FM state. Our numerical findings pave a feasible way for ZSiCNRs' novel applications in spintronics.