Abstract: The coupled numerical method of the discrete element method (DEM) and finite difference method is used to study the influences of backspin construction of steel casing between parallel tunnels. A numerical model is established based on the field tests, and the numerical analysis method is verified by comparing the simulated values with the measured ones. The load-deformation characteristics of tunnels and soil layers under three working conditions, i.e., double-tunnel-static pressure, double-tunnel backspin and single tunnel backspin, are analyzed by numerical model. The results indicate that the transverse displacement caused by backspin construction of steel casing is 163.5% of that under the static pressure, and the transverse and vertical deformations under single tunnel increase by 32.7% and 53.4%, respectively, compared with those of double tunnels. Compared under the static pressure, the backspin can effectively reduce the convergence deformation of segments, and the convergence displacement under single tunnel is twice that under double tunnels. Under the backspin, the rotation index increases first and then decreases with the vertical displacement of the steel casing, and the maximum value occurs near the displacement of the casing to the tunnel arch. Under the static pressure, the dislocation of the segment caused by vertical rotation should be focused. Under the double-tunnel-backspin, the stratum displacement caused by horizontal displacement of soil at the initial stage of construction should be concerned, and the possible mechanical overturning and the vertical error of steel casing caused by vertical displacement of soil at the later stage of construction should be focused. The stress distribution area and characteristics of tunnel segment are closely related to the dynamic construction process of steel casing, and the corresponding segment reinforcing measures should be adopted at different stages.