The authors studied the effects of the percentage and the size of wood flour on the viscosity and sedimentation of polyurethane wood filler used for furniture products. The results showed that: the viscosity of polyether composition increased when the m（wood flour）∶m（polyether polyols） greater than 7∶100 or the wood flour size was less than 80 mesh.The wood flour sedimentation rate decreased when the wood flour percentage or mesh size increased.