In order to explore the influence of suspension performance and saddle structure parameters on the handling stability of articulated vehicles，an anti-roll hydraulically interconnected system was proposed for single-axle semi-trailer suspension. Firstly，the frequency domain model of single-axle hydraulically interconnected suspension was established and verified by the roll displacement transfer function. At the same time，effective stiffness and damping were obtained according to the theory of complex mode vibration. On this basis，an articulated vehicle coupling Hydraulically Interconnected Suspension（HIS） model with saddle characteristics was presented to conduct the simulation. The results show that the hydraulically interconnected suspension system can only enhance the roll stability of the semi-trailer when the saddle stiffness parameters are not taken into account. When the roll stiffness parameters of the saddle are considered，the roll stability，yaw stability and coordination stability of the tractor and semi-trailer under the HIS system are improved，and the improvement effect is more significant when the yaw stiffness of the saddle is increased or the distance between the saddle and mass center of the semi-trailer is reduced. The results provide a theoretical basis for the design optimization of the articulated vehicle fitted with hydraulically interconnected suspension.