Abstract: This paper summarized systematically the previous investigations on the controlling factors,mechanisms of anisotropy for hygroexpansion in wood at moisture equilibrious state and the studies of hygroexpansion in wood at non-equilibrious state.Moreover,some expectations for future research were proposed on this basis.The purpose of this paper is to provide other researchers with an overall understanding about the studies in this field,and further promote the research to a new and higher level.