In the course of whole precipitation-runoff,the concentration of the non-point source pollutants in runoff changes are monitored and studied.The results are as follows:the concentration of every pollutant is high in early stage of producing flow,then tends to decline.For the soluble pollutant,the concentration ranges small,like milder wavilness in the course of whole precipitation-runoff.As for difficult dissolving pollutant,particularly for total phosphorus,the concentration in the course of whole changes acutaly like zigzag.This indicates that there is certain confinement to the concentration scope dissolved and achieved for dissolve component under a certain water environment condition.Its dissolving characteristics are influenced obviously possibly by the water environment condition than by the flow rate change.