Abstract: A model for the back analysis of elastic moduli based on the measured displacements of excavation is suggested for cut slopes in this paper . And on the account of the existance of several minimums of the objective function and the dependence of convergence on initial values in conventional optimization methods, a new optimization method for inverse problems is formulated. The method first uses the scalar characteristics of elastic problems to reduce optimization variables by one, and then transforms the multivariate problems into a series of univariate problems by recursive technique, making convergence irrelevant to initial values. Numerical test for a three media cut slope has verified the applicability of the above mentioned model and method.