Abstract: Described in the paper is a technology concerning low-investment modification of the sawing system for welded pipe length-cutting.With PLC as central control unit,and rotary coder and proximity switch,etc.as measuring elements,the modified electromechanically-operated sawing system is free of the common shortcomings as the old type sawing system stays with such as inaccurate length-measurement and reliability deficiency and so on.With so low an investment of about 20,000 RMB yuan,the new sawing system is capable of satisfying the need for normal production,and features reliable control,consistent operation and high length-measurement accuracy.