Abstract: The experimental research on the production of 20G and 12Cr1MoVG steel high pressure boiler pipes, with the final rolling temperature controlled on hot expanding mill instead of with normalization or normalization plus off-line temper, proves that the purpose of temperature control replacing normalization can be obtained by final temperature and expanding passes which are properly set. The various targets of the properties of 20G and 12Cr1MoVG steel high pressure boiler pipes produced according to the technology can meet the requirements of GB5310-1995 Specification, solving the problem of deformation of large diameter pipes with middle wall thickness （wall thickness ≤ 20mm） after their heat treatment.