Abstract: Xinjiang，as the country′s main cotton production area，is rich in cotton straw resources but has low utilization of cotton straw resources.Since comminuted cotton straw can be used to feed for cattle and sheep，how to bag comminuted cotton straw has certain practical significance for solving problem of feed for cattle and sheep and promoting commercial development of cotton straw.Therefore，it is very necessary to design a cotton straw spiral compression bagging machine.Structure and principle of whole machine of cotton straw spiral compression bagging machine were introduced.Its main components were designed and its productivity and power consumption were determined.Through finite element simulation of variable pitch spiral of its key components，reliability of variable pitch helical structure strength was verified.Finally，according to prototype′s specific power consumption index，indoor bagging tests were carried out.Results showed that the greater the speed at critical speed，the higher the transmission efficiency and the greater the amount of feed without causing clogging，the higher the delivery efficiency.