Abstract: Thermo mechanical treatment can change the basic properties of agricultural straws.Effects of thermo mechanical treatment on pH value,buffering capacity and free radical of agricultural straws were investigated.The results showed that the pH value and buffering capacity of agricultural straws were higher than that of common wood,on the other hand,the surface free radicals were much lower than that of common wood.Thermo mechanical treatment signifcantly reduced pH value,buffering capacity of the straw.Meanwhile,the free radicals on the surface of straw increased to 5～7 times.These indicated that the thermo mechanical treatment would improve the performance of straw based panels made with UF resin.