To solve the problems of frequent occurrence of lateral instability and abnormal wear of the tread surface during the service of high-speed trains, the stiffness characteristics and its parameters optimization of the rotating arm rubber node were analyzed in this paper. A high-speed train dynamic model was established using the dynamic analysis software Universal Mechanism with a type of 350 km/h high-speed train in China as the research object. Based on the mechanism of primary and secondary vehicle instability, the phenomena of abnormal hunting of the vehicle body and abnormal vibration of the bogie was reproduced through simulation, and the vehicle response and hunting characteristics were analyzed. The Poynting Thomson model, which can represent the stiffness frequency variation characteristic of rotating arm rubber node, was optimized by the genetic optimization algorithm. The research results indicate that the optimized arm node has a significant inhibitory effect on the instability of primary and secondary hunting movements.