In order to seal the void defects in CrN coatings so as to enhance its mechanical and tribological properties, the electrochemical polarization treatment at different over-potentials was employed. The results showed that the maximum content of oxygen was increased by 1.22 at% after electrochemical polarization treatment, but the crystal structure of CrN(111) and Cr2N(002) for CrN coatings remained stable. The formation of a little chromium oxides as expected sealed the CrN coatings pores, and therefore lowered its porosity from 16.79% to 12.28%. As a result, the maximum hardness was increased by 20.3%. Moreover, the wear resistance of CrN coatings was enhanced by 29.9% whilst the friction coefficient was reduced by 25.2% at the over-potential of 70mV.