Abstract: At present, when calculating deformation of foundation pits, it is unreasonable to use linear elastic spring to simulate the soil in the passive area. In order to make the calculation of foundation pit deformation closer to the actual monitoring results, the spring reflecting the non-linear deformation characteristics of soil should be used to simulate the soil in the passive zone during the calculation. In this study, a hyperbolic function soil spring model is established, and the parameters of non-linear spring in the passive zone of more than 30 foundation pits are analyzed based on the monitoring data. For a typical project, the parameters of the non-linear spring are obtained by the in-situ testing method. Based on the back analysis results, the correlation between the parameters obtained by back analysis and those obtained by in-situ testing is discussed. The results of this study can be used for reference when introducing non-linear elastic spring to improve the algorithm of foundation pits.