Abstract: Aiming at the problem that the measuring of axial force is greatly disturbed by the normal force, a modified axial force element of sting balance is proposed. By means of theoretical analysis and finite element simulation, the deformation of axial force element under axial force and normal force is obtained. Meanwhile, mechanical analysis has been carried out to get the characteristics and reasons of the deformation of the measuring beam under normal force. The deflection angle between measuring beams and main beams of the modified structure is specific, and it is not 90°, which is obtained by linear fitting between the ratio of the interference of normal force on axial force to the output of axial force and the deflection angle. Simulation result of the modified structure shows that the axial force output is only reduced by 2.77%, moreover, the interference of normal force is reduced by 99.32%, compared to the conventional axial force element. The modified axial force element can obviously reduce normal force interference on normal force, so it can be used for wind tunnel aerodynamic test with large lift-to-drag ratio requirement.