Abstract: Design method of a new contractive curve for the wind tunnel contractive segment is introduced in this paper, namely the design of contractive curve of the parameter based on UG. The performance of contractive curve was simulated by Fluent. Favorable flow field quality is attained. A new design idea for design of the wind tunnel and flow optimize is offered. A low-speed wind tunnel with this contractive curve was made,and the flow field of this wind tunnel was measured. Contrast of the simulation result and experiment result, and the analysis of the performance of the flow field were made. The design idea can be used to other wind tunnel design.