With Vanadium ion implantation semi-insulating 4H-SiC layer has been investigated. For n-type and p-type 4H-SiC, resistivities have been reached 7.6times106middotcm and 1.6times1010middotcm respectively after 1650degC annealing. Perfect surface morphology has been observed using a simple Carbon coating film protection. The Vanadium energy levels in forbidden band of n-type 4H-SiC were confirmed as 0.8 eV and 1.1 eV by different measurements.