Abstract: A fixing device is adapted for installing on a water filter which includes a base seat and an outer shell. The fixing device includes first and second curved members adapted to be clipped on a junction between the base seat and the outer shell, and a fixing module. The fixing module includes a hook member and a fastener unit that includes a handle member and a ring member which is removably engaged with the hook member. The handle member is pivotable between a fastened position and a released position, where the ring member is permitted to be disengaged from the hook member to release the first and second curved members from the junction between the base seat and the outer shell. A water filter including the fixing device is also provided.