Abstract: Natural decay resistance of Popu lus delioidcs Bartr. Var delloides cv. ’Lux’ is determined by soil-bloek method. The test results show that weight loss percentage of this species of wood attached by Coriolus versi color and Gloeop-hllum trabeum arc 51.72% and 71.55% after 9 weeks, respectively, belonging to "non-resistant" species. By observing the hyphal distribution and the penetration in wood cells and microstructural changes of cell walls, the process of degradation of wood cell walls are revealed.In order to improve the decay reistance of the specie of wood, 6 types of wood preservatives are treated at various retention, so that the decay resistance of treated wood are all improved. In particular, CCB (Chromated Copper Borate) is of great effectiveness. Decay resistance of tJeated wood can reach up to the grade of very resistant wood.