Abstract: Elaborated in the paper are the control system of the mechanical tube expander as imported by Bohai Equipment Julong Steel Tube Co.,Ltd.,and the operation principle thereof,and the process flow of the expanding machine proper.Also detailed are the main aspects of control of the expander,including in-process control of the movements of the main hydraulic cylinder,pipe length measurement,calculation and assignment of the expanding steps,control of the walk-beam movements of the clamping car and the transfer rollers as well as control of the lifting/lowering movements of the three tube conveying rollers.The actual operation situation shows that the tube expander control system features performance reliability,high automation level,complete alarming and protecting functions for various units,and operation consistency,though there still exist some problems therewith like structural complexity and rather complicated maintenance/service procedures,etc.