The utility model discloses dosing equipment for a water treatment agent. Including a housing, the shell is of a hollow cylinder structure. A first rotating motor is connected to the middle position of the top end of the shell; an output shaft of the first rotating motor is arranged downwards; a first rotating rod is connected; the first rotating rod penetrates through the shell and extends to thebottom end of the shell; the bottom end of the first rotating rod is rotationally connected with the inner wall of the bottom end of the shell; a liquid storage tank is arranged on one side of the top end of the shell, the bottom end of the liquid storage tank is connected with a liquid injection pipe, the liquid injection pipe penetrates through the shell and extends into the shell, the inner wall of the shell is rotationally connected with a baffle, the top end of the baffle makes sliding contact with the bottom end of the liquid injection pipe, and the two sides of the baffle are connectedwith symmetrically-arranged springs. The sewage treatment agent injection device is novel in structure, the speed and the use amount of sewage treatment agents injected into sewage can be controlledregularly and quantitatively, the sewage and the sewage treatment agents are mixed more evenly, and the expected sewage treatment effect is achieved.