The invention discloses an adjusting device for a knitting machine sinker. The device comprises a frame, a triangular frame, a stabilizer bar, and an elastic adjusting piece. One end of the triangular frame is fixedly arranged on the outer side of the frame. The top end of the triangular frame is fixedly provided with an adjusting rod. The other end of the frame is provided with a handle section. The elastic adjusting piece is fixedly arranged between the frame and the stabilizer bar. The bottom end of a fixed sleeve is fixedly provided with a bottom cylinder. A plurality of pinholes are arranged on the bottom cylinder. A movable rod is sleeved in the fixed sleeve. The top end of the movable rod is fixedly connected with a limiting piece. The part of a movable sleeve between a movable plate and the fixed sleeve is coupled with a reset spring. Through fixedly arranging the elastic adjusting piece in the frame, use range of the sinker adjusting device is expanded, and the adjusting device can reduce adjusting errors generated by vibration in an adjusting process, so adjusting is rapid and convenient. The device is economical and practical, and is convenient for popularization and application.