Abstract: Protective action of TNA on rice and antidotal mechanism of TNA to chlorimuron ethyl had been studied. The rice growth was influenced at a chlorimuron ethyl residue level of 10μg·kg-1 . The higher residue level of chlorimuron-ethyl, the more inhibition of rice growth was obvious. TNA was applied at the rate of 50 mg·kg-1(Soaked seed) or 200 mg·kg-1(Treated leave ), the rices could observed recover from injury of chlorimuron-ethyl. TNA obviously increased Glutathione S-transferase (GST) activity and Glutathione (GSH), polyphenol and proline content in rice. TNA protect rice by increasing GST activity, which results in accelerated detoxification of chlorimuron-ethyl via GSH conjugation.