This paper applies the one-line (shoreline) model to a typical sandy shoreline of a harbour city in the northen part of China and the numerical model is used to simulate shoreline change. The paper consists of two parts, the first describes the principles of the shoreline model, and the proper choice of the model's parameters. As an important part, a breaking wave model, in which the combined deformation of wave refraction, diffraction and shoaling is considered, is established. A pragmatic method is used to compute the breaking wave height and angle. The second presents the results of numerical simulation of shoreline change at site. First, a calibration and a verification are carried out by the use of known wave data, topographic data and the corresponding shoreline data. Then the shoreline position at the site after five years from 1992 is forecast, and several engineering plans are proposed to protect the beach, their protecting effect is studied by the use of one-line model. The results of numerical simulation agree with the shoreline change situation observed fairly well.