In order to calculate the stress and analyze the stability of the rock wall and rock plate between the underground caverns, the principle of stress flow conservation, i. e. the vertical stress flow of surrounding rock of arbitrary horizontal section and the horizontal stress flow of arbitrary vertical section remain unchanged before and after tunnel excavation, is put forward based on the idea of mechanical balance. Thus, the force of each rock wall, plate and pillar in the cavern group is calculated, and the supporting structure measures are designed according to their stability. The design results of underground cavern group in Badaling Great Wall Station on Beijing-ZhangjiakouHigh-speed Railway show that, compared with the traditional empirical method and numerical simulation method, the support structure design method based on the principle of stress flow conservation has the advantages of convenient calculation, safety and reliability.