In Image super-resolution methods, the classical interpolation methods have checkerboard effect and image blur. Using the partial differential equations with the post-processing is more complicated. In this paper, it is proposed to obtain a new PDE model which is coupled between isotropic and anisotropic partial differential equations. This model is processed for image super-resolution. It does not only decrease computational complexity, but also ensures a better image super-resolution effect. The experimental results show the advantages of this method.