Helicopter simulator will simulate the automatic transition process according to the mission requirements. This thesis studies the specific automatic transition process and builds the mathematic model of automatic transition on height and speed. In allusion to the characteristic of simulator, this thesis also designs the simulation structure chart of automatic transition process in stimulator. Besides, it also utilizes the six-freedom degree and nonlinear model to stimulate the automatic transition process, finding that this method can realize the mission requirements for automatic transition process of helicopter simulator.