Based on the bifurcation theory, the levitation stability of maglev vehicle turnout beam coupling system is studied. The magnetic levitation electromagnet model, levitation controller model, vehicle system model and turnout beam model are established, and the vehicle turnout coupling model system is constructed. The dynamic levitation behavior of maglev vehicle on turnout beam is analyzed in detail. Three levitation states,i.e., steady levitation, selfexcited vibration and levitation sucking, are simulated and reproduced. The bifurcation characteristics of levitation vibration of vehicleturnout coupling system with different levitation control parameters are calculated by using the bruteforce method. The relationship between the mass and natural frequency of turnout and the stability region of suspension control parameters is studied. The results show that there are upper and lower limits for the stability region of the control parameter kp. As kp is less than the lower limit，there is the lowfrequency selfexcited vibration of the vehicle suspension system. As kp is greater than the upper limit is the coupled selfexcited vibration of the turnout. When the natural frequency of turnout is close to suspension frequency, the upper limit value of stability region of suspension control parameters is the smallest, and the lower limit value of stability region is not affected. By changing the mass of turnout, the levitation stability region can be expanded, and the coupling selfexcited vibration of turnout can be avoided.