Abstract: Effect of triethanolamine(TEM) on the drug load, retardant effectiveness and hygroscopicity of wood treated by three fire-retardants(F1,F2,DPB) were investigated. The results showed that drug loading and oxygen index increased with the increase of triethanolamine and the retardant effectiveness was improved at the same time. When triethanolamine is increased to 3.5 %, the viscosity of the solution rises and the increase of the drug loading becomes insignificant. Adding 2.5 % to 3.5% of triethanolamine gave the minimum moisture absorption rate for the samples. Otherwise the experiments showed that F2 fire-retar-dant had the synergistic effect with triethanolamine only and F1 and DPB had little synergistic effect with triethanolamine.