The invention discloses a synchronous tractor control signal conversion interface which comprises a bridge output port, a conversion interface output wire, a bridge input port and a circuit board. Thecircuit board comprises an integrated circuit and a potentiometer. The bridge input port and the bridge output port are used for the bridge connection of a sewing machine reversing stitch interface socket and plug. During the bridge process, a DC power supply and reversing pin control level are introduced into the circuit board, and the reversing pin control level is sent to an inverting input terminal of the integrated circuit. The integrated circuit is used for comparing the comparing the sewing machine reversing pin control level and reference voltage and outputting a comparison result toa synchronous traction machine through the output wire to be a control signal of an electromagnet lifting mechanism. According to the synchronous tractor control signal conversion interface, the control signal which controls the electromagnet lifting mechanism is provided for the synchronous traction machine, thus a cloth pressing synchronous wheel of the synchronous traction machine can be raisedor lowered in time according to the reversing stitch control.