As a kind of long-span underground structure, a multi-arch tunnel has a complex structure. The method without a middle guide tunnel can reduce water leakage of the middle partition wall based on improving construction speed. The purpose of this research is to study the influence degree of the construction activities of a multi-arch tunnels without a central guide tunnel on successive tunnels. Taking Chenjiatan tunnel as the research object, the deformation of the surrounding rock, the influence degree of successive tunnels, and the overturning trend of the middle partition wall under different spacing are studied by numerical simulation. The results show that when the first tunnel is excavated to the control section within 5 m, the influence on the surrounding rock is the largest, and the displacement release coefficient of surrounding rock increases by more than 40 %. When the control section is more than 10m, the release coefficient of surrounding rock reaches more than 93%, and the influence degree is small. When the control section is more than 20m, the influence degree can be ignored. When the longitudinal spacing is greater than 35m, the S value of the influence degree is close to 10%, and when the longitudinal spacing is greater than 40m, the S value is less than 10%. In terms of the overturning degree of the middle partition wall, when the excavation of the guide tunnel is completed, the inclination degree of the middle partition wall reaches the maximum, and the inclination angle is about 3.28 × 10-4; When the longitudinal spacing is greater than 30 m, the difference of inclination angle is 0.351×10-4. At this time, the inclination of the middle wall is large and the range is small, which is conducive to the stress of the middle wall. Therefore, it is recommended to control the longitudinal spacing of tunnel excavation face tunnel excavation about 30m~40m.