This paper numerically studies a lift enhancement approach for a supersonic thin airfoil with t/c of 3.2% using Co-Flow Jet (CFJ) active flow control at Mach number of 0.1. The Reynolds averaged Navier-Stokes equations with Spalart-Allmaras turbulence model are solved with high order accuracy numerical schemes. The CFJ is first applied to the flapless airfoil. It is able to achieve a high lift coefficient of 2.12 at an angle of incidence of 18deg, 141.9% higher than the baseline airfoil, but at a very large CFJ power cost with the CFJ power coefficient of 3.06. By using a flap for the baseline and CFJ airfoil at zero angle of incidence, the lift coefficient can be increased much more efficiently than using a flapless airfoil. Two methods applying CFJ on the flapped airfoil are investigated: 1) using CFJ on the front main part of the flapped airfoil; 2) using CFJ on both the front part and on the flap. For the same momentum coefficient Cµ of 0.08, the methods 2 achieves a high lift coefficient of 1.91, 42.5% higher than that of the method 1, with a CFJ power coefficient of 0.085, 7.6% lower than that of the method 1. The CL /CD and (CL /CD )c for the CFJ method 2 is 20 and 10.6, respectively. Compared with the baseline flapped airfoil with no flow control, the lift increase is 103% with a (CL /CD )c increase of 5.5%, which results in a productivity efficiency increase of 114.2%. Such a good aerodynamic performance is attributed to splitting the CFJ to two series CFJs in streamwise direction with Cµ of 0.024 used in the front and 0.056 used on the flap. The front CFJ mitigates the separation bubble on the front part of the thin airfoil and energizes the flow, the rear CFJ attaches the flow efficiently in adverse pressure gradients. Even though the total Cµ of 0.08 is the same for the CFJ method 1 and 2, each of the CFJ in the method 2 has a lower total pressure loss and thus requires lower total pressure ratio from the CFJ actuators, which reduces the total CFJ power required. Using two CFJs in series in the streamwise direction provides a high effectiveness and high efficiency lift enhancement method for supersonic thin airfoil. More study needs to be done to understand the interaction relationship between the two CFJs.