Abstract: This article deals with data compression in quadtree representation of multi-valuegray images.Quadtree is used to represent general images which have 256 values atmaximum gray range.Focusing on the structure of quadtree,first,by taking storageinto consideration,we present a method which,store the tree according to the orderof its traversal in width,so that the storage space is reduced.Second,we use typecode to make further compression of redundant information in quadtree.Severaltypical images have been selected to do experiments on the image system which iscomposed of PC-1000 and PDP-11.