Corrugated expansion joints are not only the main accessories for Roots blowers, but also common supporting parts in industrial products. Roots blower in operation will produce wall stress and push and pull; wall stress size, affecting the strength of the pipe, push and pull increase, the pipe's fixed bracket should be made very large, to withstand the pipeline expansion and contraction of the push and pull; so the use of expansion joints to compensate for the variable openings approach to reduce the wall stress and thrust. In the selection of corrugated expansion joints, the corrugated expansion joints of Roots blower can be selected according to the code on the specification model, the code of the corrugated expansion joints on the Roots blower is based on the caliber of the development of the main models include 1.0TN50x21BIF to 1.0TN800x21BIF, which includes most of the models of Roots fan.