Abstract: The two-dimension grouping method was used to select some kinds of band ratios and their combinations, which could be applied to forest classification and estimate of stocking volume. Proposed in this article was a new concept of non-linear band ratios, which, after practical application to some case, proved to have satisfactory result meanwhile, new light was cast on the mechanism of band ratio and on the role of some bands in forest, classification and in estimate of stocking volume.