Abstract: The effects of fosthiazate by soil application on the activity of soil urease,invertase and catalase were studied in greenhouse. The results showed that fosthiazate had a significant effect on the activity of soil urease with a stimulation-inhibition-stimulation curve. The effect of fosthiazate on soil invertase showed a stimulation-inhibition action,but mostly with an inhibition effect. It's found that at low application concentrations it showed a slight stimulation effect on soil catalase,while at high concentration of 60 kg/hm2 showing a slight inhibition effect. The activity of soil urease and invertase could recover gradually at fifty days after application.