Abstract: The perturbation gas film pressure governing equations and motion equation of spiral groove dry gas seals with flexibly mounted stator, which took the axial vibration of rotor into consideration, were presented based on gas film lubrication and kinetic theories. The influences of sealed pressure and spiral angle on dynamic characteristics and transient responses were researched under the condition of high-speed. It is shown that gas film sharply oscillated along a certain path when the sealed pressure was relatively low. Saltation peak and period peak of gas film thickness disturbance were defined, and their minimum values were considered as the optimization objects of seal dynamic performance. The interactions among spiral angle (typical representative of structure parameters of spiral groove), spring stiffness, secondary seal damping and stator mass were analyzed under high-speed and high-pressure conditions based on the method of full factorial design. The results show that there was an obvious interaction between spring stiffness and stator mass for period peak, and the other factors affecting dynamic performance of dry gas seal systems can be treated as independent variables to be optimized without affecting the precision of the results of seal dynamic performance.