Abstract: Fundamental properties of the timber of Populus deltoide×P. nigra cv. Chile. grown in Shuangliu County, Sichuan Province were analyzed by randomly sampling 3,5,8 and 11years old of specimen plants. The results showed that there were significant differences in the basic wood density, fiber length, extract content by 1% NaOH and the ratio between the thickness of cell wall layer and the cell diameter among different plant ages. It was showed that the differences in the basic wood density and fiber length among the 4 positions where the wood samples taken from the same plants, i.e., 0cm,130cm,1/2 and 2/3 heights of the sample trees. There was significant difference in the basic wood density caused by reciprocal interaction between age and the position where the wood specimen were sampled. There was no evident reciprocal interaction between age and sample height for other wood qualities. It was also proved that there was certain rule to show the difference in wood properties along with the change of tree ages and the positions of the specimen taken. The content of 1% NaOH extraction of wood descended from the 3 year old to 8 year old and began to increase at the 11 year old. There were no evident variations in the ratio between the thickness of cell wall layer and the cell diameter among the ages from 3 to 8 years old, while the ratio increased a little at the 11 year old. It was showed that the wood density and the fiber length increased with the increment of the age. The content of 1%NaOH extraction and the basic wood density increased, but the fiber length descended along with the increment of the height positions on the tree stem. There was no significant difference in the ratio between the thickness of cell wall layer and the cell diameter among the specimen sampled from different height positions.