On the basis of the principle of fault component integrated impedance based bus-bar protection， a new criterion adopting normalized restraint coefficient is put forward. According to the angle displacement of the fault component integrated impedance caused by current transformer（CT） saturation， the error of the angle displacement is defined and adopted as restraint coefficient to establish the new criterion. The new criterion has all the advantages of the fault component integrated impedance based bus-bar protection as well as higher security and dependability of tripping when there is CT saturation. EMTP simulation results show that it can immunize the mal-operation when CT saturation occurs outside the protection zone of a bus-bar.