The invention provides a remote sensing image change detection method and system based on mask classification, and the method comprises the steps: 1, the preprocessing of a multiband remote sensing image; 2, the single-band separation of the multiband remote sensing image after preprocessing; 3, the constructing of a single-band difference image of two-phase single-band remote sensing images; 4, the construction of a change mask difference image, and cutting the change mask difference image based on an Otsu method; 5, the multiplication fusion of a change mask with one of the two-phase single-band remote sensing images, thereby obtaining a change region; 6, the clustering of the change region through a fuzzy C mean value method; and 7, determining the change type of the change region through combination of the prior knowledge of the ground object type of the other one of the two-phase single-band remote sensing images according to the clustering results of the change region. The method and system are resistant to nose interference, can alleviate local optimum effectively, can consider the qualitative and quantitative description of an image change process, and is high in change detection precision and reliability.