Based on massive monitoring data of one metro station engineering, the back analysis method was used to obtain the soil parameters. The maximum displacements of retaining wall in every construction phase were considered as the objective function and an improved single variable optimization method incorporated with dichotomy was used to carry on the interval optimization analysis. This method realized the back analysis of soil parameters on complicated geological location by using 3D finite element method to model the pit engineering and improve the computational efficiency. The soil parameters acquired through this method were applied to the numerical calculation, and the results showed good accordance with the monitoring data.
