Nonlinear dynamic behavior is presented to analyze uncertainty of rotor-bearing-seal coupling system, and empirical parameter applicable scope, which aims to provide important empirical parameters selection and provide a basis for the actual steady operation control of the rotor. Based on Muszynska model and Capone circular bearing nonlinear oil film force model, parameter uncertain rotor-seal-bearing system nonlinear dynamic equations is deduced under the actionof sealing fluid exciting force and oil film force. Through the numerical analysis, the system bifurcation characteristics and influences have been investigated under the influence of the average circumferential speed constant. And bifurcation and dynamical behaviors of nonlinear of system with the changes rotating speed under several specific parameters are analyzed. The results show that the average circumferential speed constant have great effect on the dynamical behaviors of nonlinear system, earlier period doubling bifurcation is appeared with the average circumferential speed constant increasing, and the amplitude increases, the instability increases. Based on the above analysis, a reasonable average circumferential speed constant value range is given.