The dual-propeller propulsion compound helicopter has variable flight modes.The transition phase is a necessary stage to realize the conversion of different flight modes, and the asymmetry effect of propellers on both sides intensifies the coupling between lateral and heading attitude.In order to ensure the compound helicopter flight safety in transition flight phase, a lateral and heading attitude decoupling control system is designed.To solve the problems of control mode conversion and manipulation coupling between lateral and heading channels in the transition flight phase of compound helicopter, a linear transition strategy of control modes taking control efficiency as the constraint is formulated.Based on the explicit model tracking decoupling control theory, the attitude controller with control matrix decoupling is designed, and the simulation model of the lateral and heading attitude decoupling control system is constructed.The simulation results show that the control system can effectively ensure the smooth transition of the compound helicopter control modes and realize the lateral and heading channel decoupling control.