Effect of acetochlor,butyl,spring lot,trifluralin,four commonly used herbicides,on soil enzymes and soil respiration was studied.The results showed that activity of soil dehydrogenase was inhibited by four kinds of herbicides to some extent.The higher the concentration of herbicide applied,the more obviously the inhibition.Soil respiration was slightly raised by four kinds of herbicides at initial stage,but decreased 5 days later,and returned to normal 12 days later.