The static pressure regain blast pipe equalizing static pressure is applied widely in engineering. However，so far it lacks a more perfect mathematical mode1. Using basic knowledge of Fluid Dynamics，this paper estah1ishes mathematical model of basal geometry of blast pipe equalizing static pressure based on the pressure regain principle. Therefor basal theoretical curve is obtained，and cardinal physical and geometric parameters which effect geometric form of the curve. The theoretical guide for engineering design is provided. Also from practice，this paper analysed advantages of using static pressure regain blast pipe equalizing static pressure in blowout Wind system of large and high speed electronic computer and volue of engineering application，and main questions.