Abstract: Three clones of 2-,4-,5-,6-,7-,9-and 12-year-old of Populus × euramericana cv.'N2136'were randomly selected from plantations grown at the spacing of 3 m×4 m from Jianping County in Liaoning Province.For each clone,5 cm disks were taken from 40 cm,1/2 and 2/3 heights for measurement and analysis for basic density,fiber length,and ratio of wideness to space and 1% NaOH extractant of wood.Their heights,DBHs and diameters on 1/3 and 2/3 whole height were also measured and analyzed.The results showed that there existed significant difference of four wood qualities among clones of different ages.It also proved that the interaction between age and height of wood qualities did not exist or was not significant.Although no uniform trend in the changes of all wood qualities at different heights were observed,it was found that all qualities showed increasing or decreasing trends with ages and no clear pattern was indicated.Relationship between the early and the late for wood and growth of was analyzed,which showed relative coefficients between the early and the late were significant.According to the relative coefficients,early selection could be undertaken for wood qualities and growth in late age.It also suggested that early and late utilization of wood should be carried out during 4th-and 12th-year.