A precise filtering device comprises a box body, a box cover and a supporting seat; the box cover is mounted at the top end of the box body; the bottom end of the box body is supported by the supporting seat; a liquid inlet device is mounted at the middle end of the left side of the box body; a liquid draining device is mounted at the lower end of the right side of the box body; a left impurity collecting box is mounted on the left side at the bottom end of the box body; a right impurity collecting box is mounted on the right side of the bottom end of the box body; a filtering basket is mounted at the inner left end of the box body; an impact stirring device is mounted within the filtering basket; a front filter screen, a middle filter screen and a rear filter screen are mounted at the inner right end of the box body and at the lower end of the right side of the box cover from left to right. The precise filtering device provided by the invention can effectively filter impurities in water flow and has the advantages of high filtering efficiency, good filtering effect, long service life and easiness in detaching and overhauling.