The effects of coordination complexes of the rare earth (La Nd) chlorides with imidazole and simple chloride salt on bacteria, mold and enzyme activity in field soil are determined in the laboratory. The result of the determination shows that the coordination complexes of rare earth used on experiment, when their concentration is less than 1. 5 mg/g, have little effect on biological activity of the field soil; When their concentration is more than 3 mg/g. they have inhibitory effect on bacteria, mold, catalase and dehydrogenase in soil. In the coordination complexes of the sample soil, whose concentration is 15mg/g, inhibitory effect on bacteria is 47%-63%, on mold is 23%-34%, and on soil-catalase is 9. 5%-38. 7%, dehydrogenase activity obviously decreases; Therefore attention should be paid to the effect of rare earth used in agriculture soil microenvironment.