This machine knits round HDPE monofilament yarn into mesh bag for holding fruit, vegetables or used as protective net. It applies new cams and will be easier to regulate fabric density. The knitted bag will not extend and it will keep its shape well. The machine adopts transducer to adjust cylinder running speed then regulate knitting rate. It has slow-start function; also can change knitting speed at random. Slow-start and machine speed changing randomly can not only help the new machine grind in, but also conducive to observation of the machine running conditions and product quality situation.