The present invention discloses a fluid filter for screening carbon-microparticles exhausted from diesel engines, such filter has two types of structure, i.e. the plate type and the preferable tube type, which includes plurality of multilayer corrugated filtering rings and flat filtering rings, a central tube, and an outer casing; the innermost layer of the flat filtering rings is welded onto the central tube, and the outermost layer of the flat rings is welded onto the outer casing; the multi-layer corrugated filter rings are coaxially alternated within the flat filtering rings and formed with a zigzag manner, wherein side edges of each of the corrugated filtering rings are respectively welded onto neighboring flat filtering rings so as to form a continuous filter core with ‘Z’ shaped side endings, wherein two sides of the Z shaped side endings of said filter core are alternatively applied as fluid inlet and fluid outlet.