A control structure capable of adjusting water volume and controlling water supply comprising: a fixer comprising a retaining rib arranged around an inner wall of the fixer; a valve stem comprising: an inlet defined in the valve stem, a fixing rib arranged on a first end of the valve stem, an opening formed on a second end of the valve stem, the opening formed on the second end of the valve stem communicating with the inlet, and a guiding column extending outward from a side of the opening, the guiding column having a diameter less than a diameter of the opening and having a seal ring fitted thereon; a body comprising: a water outflow segment formed on a first end of the body and configured to connect with a watering tool, and an accommodation groove configured to accommodate the fixer and the valve stem, the valve stem communicating with the water outflow segment of the body; a controller for coupling with a water supply pipe, the controller comprising: a screwing section arranged on an outer wall of the controller, an inflow aperture formed on a middle section of an inner wall of the controller, and a shoulder formed beside the inflow aperture; and an adjuster comprising a threaded orifice screwing with the screwing section of the controller and fitting with the guiding column, wherein the fixing rib of the valve stem retains with the retaining rib of the fixer so as to limit a rotation of the adjuster along the body. a fixer comprising a retaining rib arranged around an inner wall of the fixer; a valve stem comprising: an inlet defined in the valve stem, a fixing rib arranged on a first end of the valve stem, an opening formed on a second end of the valve stem, the opening formed on the second end of the valve stem communicating with the inlet, and a guiding column extending outward from a side of the opening, the guiding column having a diameter less than a diameter of the opening and having a seal ring fitted thereon; an inlet defined in the valve stem, a fixing rib arranged on a first end of the valve stem, an opening formed on a second end of the valve stem, the opening formed on the second end of the valve stem communicating with the inlet, and a guiding column extending outward from a side of the opening, the guiding column having a diameter less than a diameter of the opening and having a seal ring fitted thereon; a body comprising: a water outflow segment formed on a first end of the body and configured to connect with a watering tool, and an accommodation groove configured to accommodate the fixer and the valve stem, the valve stem communicating with the water outflow segment of the body; a water outflow segment formed on a first end of the body and configured to connect with a watering tool, and an accommodation groove configured to accommodate the fixer and the valve stem, the valve stem communicating with the water outflow segment of the body; a controller for coupling with a water supply pipe, the controller comprising: a screwing section arranged on an outer wall of the controller, an inflow aperture formed on a middle section of an inner wall of the controller, and a shoulder formed beside the inflow aperture; and a screwing section arranged on an outer wall of the controller, an inflow aperture formed on a middle section of an inner wall of the controller, and a shoulder formed beside the inflow aperture; and an adjuster comprising a threaded orifice screwing with the screwing section of the controller and fitting with the guiding column, wherein the fixing rib of the valve stem retains with the retaining rib of the fixer so as to limit a rotation of the adjuster along the body.