Abstract: The laws of effects by deformation temperature and deformation amount on the structure and properties of HFW casing are investigated by means of hot-deformation test to the casing with the Gleeble-3500 thermal simulator. Also studied are the laws of effects by hot-stretch reducing + over-length heat treatment process on the structure and properties of HFW casing. The test results show that along with rising up of the deformation temperature and increasing of the deformation amount,the structure of base metal and that of weld zone are getting consistent with each other, and that thanks to the said combination process,not only the structure difference between the HFW pipe’s base metal and its weld zone is reduced,and also the comprehensive properties of the pipe are improved.