Abstract: Taking the 3.6 kV/2500 A vacuum bypass switch equipped with a single-stable permanent magnet operating actuator as the research object, firstly a three-dimensional physical and mathematical model is constructed. By using the finite element numerical simulation method, the existing uncertainty problems of structural parameters and external excitation of the operating actuator are focused on. Moreover, the chaos polynomial expansion (PCE) method is adopted to analyze the influence of structural parameters and external excitation changes on the probability distribution of the average velocity and final velocity of the operating actuator, and the reliable interval threshold values of structural parameters and excitation parameters are obtained.