Abstract: The conditions of the magnetism-bearing blank tube are analyzed by means of measuring the residual magnetism of the SAWH tube as remaining during the operation process.Accordingly magnetic induction，magnetic field strength and magnetic flux of the tube are calculated，based on which measures to reduce tube end magnetism are proposed.The analysis result leads to such a conclusion that connecting the cathode to the pipe outer surface area that is close to the weld point can shorten the current path length，and thus obviously reduce the tube end magnetism.