By means of X-ray diffraction and adsorptional test, The degree of relative crystallinity (C,r1,%) of the wood cellulose in the stem of Larix gmelinii Rupr. was determined. The results of the experiments are given as follows:1. There are differences of the C,r1,% in different parts in larch cross section. The immature wood is the lowest, the heart wood is the medium and the sapwood is the highest. After steaming high-temperature drying, the C,r1,% of the three parts have been increased respectively. The C,r1,% of the immature wood is from 54.3% to 55.1%, the heart wood is from 57.5% to 59.5% and the sapwood is from 59.6% to 60.1%.2. The adsorption of wood is a very important physical property and the effective factors are too many. So when the adsorption of wood is studied, we must consider the various factors, such as the chemical components and anatomical structure of wood.