Combined with the related research work both domestic and overseas, this paper proposes a method to realize the direction change of the airflow from the BWB(Blended Wing Body)) aircraft engine by deflecting the horizontal tail, as consequence to achieve the deceleration purpose. Based on solving the three-dimensional Euler’s equation, the flow field distribution characteristics and reverse thrust near the nozzle of BWB aircraft under different tail deflection angles are numerically simulated, and the gain in landing field length is evaluated. Aerodynamic and performance calculations show that, within the speed limit, the engine jet airflow will impact the deflected tail, which will generate a reverse jet flow and generate a large reverse thrust, effectively reducing the landing field length. And as the deflection angle of the tail increases, the reverse thrust and deceleration effects gradually increase.