The external enclosed large threephase wound asynchronous motor slip ring, brush holder, the design of the ventilation structure were mainly introduces. The structure of the cooling system were design, and the key point in design was pointed out. The enclosed large threephase wound asynchronous motor collector ring each slip ring temperature uniformity, collector ring design and actual test results anastomotic theory were verified. The enclosed collector ring carbon powder collection device was practical and motor the feasibility of local structure.