In the paper, analyzing the tread flange structure characteristics, its injection mold is designed and the maneuvering tread demolding way is applied to get out flang tread. When designing demolding parts, hydraulic pressure motor and chain-gear mechanism are used. Besides, parting plane and the forming parts can be gained automatically in Pro/E(Pro/Engineer Wildfire3.0) and standard moldbase can be achieved by EMX4.1 including gating, cooling, and guiding system, etc. The designing ways and structure is proved rational and can be taken as reference for the similar injection mold especially for those with longer tread.