In this work we have proposed an iterative method for direct determination of relaxation parameters from low-energy electron diffraction (LEED) intensity patterns. The algorithm is based on the layer-doubling method. It is shown that, with some realistic constraints, the relaxation parameter for a single relaxed structure can be obtained, and this solution can be utilized to determine the two-layer relaxed structure iteratively. With simulated intensity patterns for a one-dimensional model, the method is found to work well.