To explore a jet control method for enhancing the aerodynamic performance of airfoils at small angles of attack so as to realize rudderless flight control, inspired by circulation control, it was proposed to arrange the jet at the lower surface of the NACA0012 airfoil near the trailing edge, and optimize the aerodynamic control effect of (jet on the lower surface of trailing edge) LSTE jet by analyzing the flow states and parameter variations. Firstly, three sets of grids with different scales were used to simulate the NACA0012 airfoil, and the convergence and effectiveness of the numerical simulation method were verified. Secondly, the mechanism of the influence of LSTE jet on the aerodynamic performance of the airfoil was studied by comparing the changes in the distribution of Mach number, streamline, and pressure distribution of the flow field. Finally, the variations of the aerodynamic coefficients of the airfoil with the position, the momentum coefficient, and the forward angle of the jet were analyzed. Results show that LSTE jet induced a counterclockwise vortex at the trailing edge, forming a low-pressure separation zone, which deflected the main flow of the trailing edge and increased the effective camber of the airfoil, and the suction peak of the leading edge also increased, thereby increasing the lift coefficient. The closer the LSTE jet was to the trailing edge, the greater the momentum coefficient was, and the better the effect of lift increase and drag reduction was, but the angle of attack of the airfoil decreased by 1° to 3°. Under different angles of attack and jet flow coefficients, the maximum lift and minimum drag of the airfoil could be achieved between γ=60°-70° at the same time. LSTE jet can effectively change the aerodynamic performance of the airfoil at a low angle of attack, and has certain significance for the realization of aircraft rudderless control.