Under the humidification condition, the strength parameters of the expansive soil will decrease and the expansion force will be generated. Under the combined action of the two, the stability of the surrounding rock of the expansive soil tunnel will be seriously reduced. Stress is very necessary. In this paper, laboratory tests and numerical simulations are used to study the stability of the surrounding rock of the expansive soil tunnel. First, the shear experiment is carried out on the remolded expansive soil with different water content, and the fitting relationship between friction angle and cohesion and water content is obtained. Then, the ABAQUS finite element software is used to simulate and analyze the excavation process of the expansive soil tunnel, and the temperature field module is used to simulate the humidification and expansion of the surrounding rock of the tunnel. To analyze the influence of various factors on the stability of the expansive soil tunnel. The results show that after the surrounding rock is humidified, the stress value at the arch waist of the surrounding rock increases significantly, the stress value at the vault and arch bottom decreases; the longitudinal displacement value at the lining arch bottom increases, and the longitudinal displacement value at the arch top decreases . By designing orthogonal experiments and using range and variance analysis, the most influential factors on the stability of the surrounding rock of the expansive soil tunnel are the humidification strength, followed by the over-span ratio, the swelling thickness and the swelling coefficient. The research results can provide a basis for the construction safety and design optimization of the expansive soil tunnel.