Abstract: Metallic hafnium possesses a combination of properties that makes it the preferred material for control rods of nuclear reactors.To prevent the irradiation deformation and the mechanical property degrade of hafnium plates,and to increase the service life of the control rods,a new-style square-tube control rod is developed.The elemental composition,mechanical property,the corrosion resistance and the physical charac-teristics of hafnium are studied during the development.Some verification tests of the control rod are carried out after the manufacture,which prove that the design and manufacture of the new-style control rod meet the requirement of the technical conditions.The control rod has an approved mechanical property,and the service life can be increased effectively.