Abstract: A method to calculate the displacement of cutting face of composite soil nailed walls was introduced.The method was based on the conception that incremental relief of in-situ stress generated incremental displacement on the cutting face.A release force was employed to realize the idea.Some displacement was accumulated on the cutting face when the release force was exerted.The total displacement was composed of 3 kind of sub-displacements: diselacement by release force,additional displacement of upper cutting face by the movement of the current step and additional displacement of lower cutting face by the movement of the current excavating step.A simple formula was set up with simple theory to calculate the total displacement of the cutting face.Two practical composite soil nailed walls located in layered soil were calculated with the present method.The results were close to the measured displacement.