Abstract: Addressing the repeated occurrence of non-conformance of mechanical properties of the 17-4PH largesized centrifugally-cast cast tube,the main possible causes are analyzed.As a result it is identified the major causes are the unreasonable manufacturing process path,and the improper control and operation of the heat treatment process.Accordingly the manufacturing process path for the tube is optimized by means of such actions as pre-solution rough machining of both inner and outer surfaces of the tube,strict controlling the heat treatment process parameters,keeping the solution transfer time within 40 s,and the cooling water temperature under 32℃,etc.,which finally gets the mechanical properties of the said centrifugally-cast tube stabilized,and the primary qualification rate thereof up to 95%~99%.