During the construction of the connection gallery by shield method, the structural system varies and the lining stress redistributes, which is bad for the stability of main tunnel. In order to lean the safety and response of the structure, a fullscale experimental study on structural mechanism of the connection gallery by shield method is carried out. In the experiment, the 7 ring segments are assembled at different joints for simulation. After simulating the real soil and water pressure load, the exit process of the real connection gallery by shield method is simulated by directly cutting the segments with shield. The results show that: （1） Through the simulation, the key working condition nodes in the construction process are obtained. （2） Through the simulation, it is concluded that the convergence deformation of each ring in the whole cutting process is good and the construction method is safe. （3） During the experiment, the internal force redistribution occurs at all positions except the cutting position, and the process of internal force redistribution is closely related to the variation process of working condition.