Abstract: The influence of near wake trailers in different planes due to blade twist was accounted into Blade aerodynamic model in free wake.Leishman-Beddoes unsteady aerodynamic model was applied to airfoil model,and flapping equation of blade under manoeuvering was derived.Time-step free wake was established by coupling second-order time accurate algorithm,blade aerodynamic model,blade flapping equation and rotor trim.Then time histories of wake geometry and aerodynamic response were calculated.The time-step method was feasible by comparing the result with experimental data,and then the influence of pitch rate and pre-twist on aerodynamic response was analyzed.