To solve the problem of sealing performance in aircraft pipeline under actual working conditions,a multi-body contact finite element model of aircraft pipeline connection was established based on the structural characteristics of the expanded hydraulic pipeline connector and considering the multiple contact relationships of the connector contact pairs.Three main sealing criteria were proposed to ensure the basic sealing performance of the expanded pipeline connector,including the sealing closed loop,effective sealing area,and effective sealing pressure ratio.Using finite element simulation software ANSYS/Workbench,the variation process of pipeline sealing performance under vibration working conditions and the influence of vibration load location and amplitude on pipeline sealing performance were analyzed.The results show that the outer nut of the pipeline connector will gradually become loose under vibration conditions,leading to the degradation of pipeline sealing performance.As the vibration period increases,the loosening angle of the outer nut increases.When the amplitude of vibration load is the same,the closer the vibration load location is to the threaded connection pair,the faster the sealing performance of the pipeline connection decreases.When the vibration load location is the same,the larger the amplitude of vibration load,the faster the degradation rate of the pipeline sealing performance.To reduce the impact of vibration on pipeline sealing performance,the pipeline connector should be kept away from vibration excitation sources as far as possible,and the amplitude of vibration load should be reduced.In practical engineering applications,the deterioration process of pipeline connection sealing performance is generally mitigated by blowing fuses.