The invention discloses a filter. The filter comprises a barrel, a filter element assembly and a base, wherein the filter element assembly is located in the barrel and comprises a support connector fixed at the bottom of the filter element assembly, and a plurality of clamp rods are arranged on the periphery of the support connector; the base is located below the barrel and connected with the barrel; a support barrel is arranged in the base; a plurality of long-strip-shaped clamp grooves adaptive to the clamp rods are formed obliquely downwards from the top end of the wall of the support barrel and constitute mounting tracks for one-way rotation and deep going of the clamp rods. Fixed connection is realized through cooperation between the filter element assembly provided with the clamp rods and the base provided with the long-strip-shaped clamp grooves, so that the filter element assembly cannot be separated from the base easily, and the filtering effect is guaranteed; the resistance to the clamp rods rotationally entering the clamp grooves is small, and the mounting convenience is improved greatly.