Fiber morphology, chemical composition, main physical and mechanical properties of the thinned wood and mature wood of Pinus massoniana have been studied in this paper The results shows that the thinned wood has shorter and narrower tracheid, thinner tracheid wall, larger radio of length to width of fiber, slightly higher cellulose content, lower lignin and extraneous substance content, lower green moisture content, smaller shrinkage behavior, and stronger toughness than the mature wood's But there is n...