Abstract: In order to enable technicians to use displacement well killing method in the right way,this paper discusses the problems occurred during well Arvand-1 killing and analyzes the failure causes in the killing.When the shut-in casing pressure is 52.5 MPa,the measures taken to maintain the injection pressure 61.6 MPa then stop and reinjection when the pressure drops to 57.4 MPa,and to keep casing pressure more than 42.0 MPa to balance the pore pressure are considered improper.Although killing fluid 2.55 times borehole volume were injected,the killing was unsuccessful.If borehole volume,injection volume and treatment pressure were considered in whole,and injection pressure and exhaust pressure were reduced gradually,the well could have been successfully killed with displacement well killing method.This paper proposes the right killing method based on the principle of displacement well killing and pressure balance.