In this paper，a new method is presented for the pneumatic computation of aerobat with steering control engines at the base. The method is an organic combination of S. C. Ward's engineering method and the axisymmetric numerical simulation method developed by the authors earlier for the supersonic strong interaction flow field with transverse injection at the base. It can estimate the total propulsive forces and the additional pitching and yawing momentum coefficients，including both direct and indirect parts. The base drag coefficient C_D decreases as compared with the case without injection.