Abstract: The virtual flight test(VFT)is an effective test mothed for getting characteristics of unsteady aerodynamics when aircrafts maneuver and understanding the aerodynamics-move-ment nonlinear coupling mechanism.The virtual flight test balance development is a key tech-nique in 2.4m×2.4m transonic wind tunnel virtual flight test.We developed a special dedicated VFT strain-gauged balance to measure aerodynamic parameters for closed-loop control.The test model is long and thin because of being devided into two parts so that the balance design space is limited,and the design loads do not match extremely.The aerodynamic forces on the model’s two parts get worse due to this division.Computational Fluid Dynamics (CFD)results show that the maximum normal force on the aft half of the model reaches 12000N,and the pitch moment reaches 6000N·m.One challenging thing is that the wind tunnel test requires both measurement of forces on two separated model parts and the movement of those parts rolling around the axial shaft with low-friction together,so the normal balances don′t meet the requirements.Movement and measurement must be fully considered together.Through theoretical analysis and numerical simulation we optimized the structure of the new balance.A new assembly configuration with bearings and mandril is used for the balance,which is inside the balance and could rotate with the model together with low friction.A kind of serial twin-balance with the same earth end in the middle of the balance was measure forces on the two parts of the model.Eight components are set on four groups of sixteen beams which are located in four different sections.Different dimen-sions of these beams are optimized to solve the loads match problem and conflict of measurement and movement of model parts.During the course of design,the balance stress and strain analysis optimization was generated by finite element simulation method using software ANSYS,and then combined bridges are schemed.Both calibration and wind tunnel test results show that the balance meets all requirements of VFT research.