Abstract: The inversion analysis is an important way to obtain the geotechnical strength parameters，especially，for weak intercalated layer slope，weighted displacement back analysis is an effective method to get its soil parameters. Based on the inclination data and basic idea of block division，a new calculated approach for displacement weight was proposed. By displacement curve and least square method，the slope soil was divided into several blocks with different displacement characteristics. The displacement for single block could be expressed by two variables: sliding and deformation displacement. The deformation displacement，which reflects itself soil strength，was regarded as the weight of weighted back analysis. And the new inversion objective function was presented. Finally，depending on entity project，this presented method was used to calculated soil strength which matched well with the test values. Meanwhile，the sensitivity result also indicated the effectiveness of the method.