[Abstract] Objective To study the toxicity of rats that caused by long-term intake of low-dose Clethodim Technical and determine the maximal non-effect of Clethodim Technical, in order to provide the reference dose for safety in production and chronic toxicity experiment. Methods A total of 80 SD rats(half female and half male) were randomly divided into 4 groups, respectively, for the orginal drug 14.9mg/kg?bw?d group, 89.6mg/ kg?bw?d group, 537.5mg/ kg?bw?d and normal control group based on body weight. Execute the rats meanwhile detect the indexes including hemology、biochemistry detection of serum、body weight and organ module after the end of the experiment, and the results were analyzed statistically. Results and Conclusions When the oral dosees of Clethodim Technical at 200 mg/ kg?bw?d and above, it can cause toxic effects on rats, and its maximal non-effect dose of long-term intake of low-dose Clethodim Technical on rats is 40 mg/kg?bw?d.