Abstract: An analytical model for predicting the aeroelastic behavior of hingeless rotor blade with arbitrary section was presented, and the effect of composite flexures on aeroelastic stability was investigated. The analysis of rotor blade was simplified as a line sectional properties analysis and a nonlinear beam analysis. Sectional properties included the in and out of plane warping deformation and the one-dimensional moderate deformation theory was used for the aeroelastic behavior of composite rotor blade. The quasi-steady strip theory with dynamic inflow effects was used to obtain the aerodynamic loads acting on the blade, based on finite element theory, formulations of hingeless rotor blade system aeroelastic stability calculation was developed. In the present work, the aeroelastic behavior of hingeless rotor blade system with composite flexures was studied. Numerical tests was carried out for the valid of the aeroelastic model. The numerical results show that the structural couplings of the composite flexures has great effects on the aeroelastic stability of the rotor system blade, and based on the relations between aeroelastic stability and ply angle, an advanced composite rotor blade would be obtained.