Aiming at the hydraulic pipeline of civil aircraft with expansion rings,combined with international airworthiness standards,the objective functions related to the four parameters of bending angle,bending radius,span and height of expansion rings were established with the optimum static and dynamic characteristics and the lightest weight of the pipeline as the optimization objective.The dimensions of different functions were unified by the analytic hierarchy process,the multi-objective optimization problem was turned to the single-objective optimization problem.The weight coefficient of the objective function was adjusted to reflect the different importance of multiple objectives.The importance of multiple goals was reflected by the weight coefficient.Finally,the dynamic mathematical model of expansion ring was verified by experiments.The results show that the mathematical model of expansion ring dynamics is accurate,and the genetic algorithm of analytic hierarchy process can be used to weigh the comprehensive characteristics of pipeline and the reasonable structural parameters of expansion ring areobtained.