Research conclusions: In actual construction practice, value m is less than both theoretical value and experimental value. Whether the selected value m is reasonable or not will seriously affect the calculation results of the endogenous stress and the deformation of the bracing structure of foundation pit. Furthermore, it can become the key factor of influencing the selection of bracing project and bracing structure design. In addition, value m, must be calculated by different methods in the same state. Otherwise, the results would deviate greatly, resulting in losing the significance of counter-analysis.