Abstract: In order to develop and optimize the electronic let-off system and improve the compatibility of warp knitting machine and product quality,this paper analyzed the control procedure of the multi-speed electronic let-off system,and elaborated on how the beam-motor to switch between different speeds according to the speed of principal axis,outside perimeter of beam.It discussed the control algorithm of multi-speed electronic yarn let-off system,and worked-out the value of motor speed operation according to the speed of principal axis and process requirement.The practical weaving has proved that the error in let-off of this system can be controlled in±1% and accurate let-off is ensured.