To study the characteristics of the surface of wood fibers.including the surface tension and its variation at different temperatures,contact angles have been measured and regression has been theoretically calculated.Results show that the surface tension of fir,poplar and bamboo wood fibers at 25℃ is 46.75,40.01 and 31.01mJ/m~2,respectively.After high temperature treatment,the surface tension of poplar and bamboo wood fibers drops largely,by 16.39%and 14.16%respectively.Moreover,the polarities of surface tension of wood fibers decline greatly,which indicates that wood fibers after high temperature treatment are more suitable for preparation of wood-plastic composites.