Nonlinear aerodynamic model and flight dynamics model of the quad tilt rotor aircraft are developed by calculating the airframe forces and moments of each component, including rotor, wing and fuselage. A simulation model is built under the Matlab/Simulink environment, then according to the simulation model, the control efficiency of each control surface is calculated, and the control methods used for each channel in different states are determined. Combining the flight dynamics model with control mode, the trimming value with the whole envelope is calculated on the longitudinal channel. The feasibility of manipulation strategies is verified.