A switch valve unit, comprising: a valve seat which defines a valve cavity having an open bottom end port; an at least partially axially deformable diaphragm member which is mounted in the valve cavity to divide the valve cavity into an upper cavity portion and a lower cavity portion, and provided with a first hole and a second hole spaced from each other for providing fluid communication between the upper cavity portion and the lower cavity portion; a button axially movably mounted on the valve seat; and a valve rod assembly connected to the button so as to follow the movement of the button, extending through the valve seat and into the upper cavity portion, and having a first position in which the first hole is sealed and a second position in which the valve rod assembly disengages from the first hole; wherein the valve seat at the top thereof includes a central protrusion, and a surrounding wall surrounding the central protrusion, and defined between the central protrusion and the surrounding wall is a receiving space for receiving the button, wherein the central protrusion and the surrounding wall comprise at least one vertical ridge and vertical groove, and arranged between the button and the valve seat is a third spring; wherein the switch valve unit further comprises a cover member mounted on the button, the switch valve unit being characterized in that, the button comprises at least one vertical ridge and vertical groove corresponding to the at least one vertical ridge and vertical groove of the central protrusion and the surrounding wall, and in that provided between the cover member and the button are a snap-fit means formed by cooperation between an expansion portion and a snap jaw, and an anti-rotation means which include formed on the cover member, first vertical ridges and first vertical grooves between the first vertical ridges; and formed on the button, second vertical ridges and second vertical grooves between the second vertical ridges, wherein the first vertical ridges are configured to be received in the second vertical grooves, and the second vertical ridges are configured to be received in the first vertical grooves. a valve seat which defines a valve cavity having an open bottom end port; an at least partially axially deformable diaphragm member which is mounted in the valve cavity to divide the valve cavity into an upper cavity portion and a lower cavity portion, and provided with a first hole and a second hole spaced from each other for providing fluid communication between the upper cavity portion and the lower cavity portion; a button axially movably mounted on the valve seat; and a valve rod assembly connected to the button so as to follow the movement of the button, extending through the valve seat and into the upper cavity portion, and having a first position in which the first hole is sealed and a second position in which the valve rod assembly disengages from the first hole; wherein the valve seat at the top thereof includes a central protrusion, and a surrounding wall surrounding the central protrusion, and defined between the central protrusion and the surrounding wall is a receiving space for receiving the button, wherein the central protrusion and the surrounding wall comprise at least one vertical ridge and vertical groove, and arranged between the button and the valve seat is a third spring; wherein the switch valve unit further comprises a cover member mounted on the button, the switch valve unit being characterized in that, the button comprises at least one vertical ridge and vertical groove corresponding to the at least one vertical ridge and vertical groove of the central protrusion and the surrounding wall, and in that provided between the cover member and the button are a snap-fit means formed by cooperation between an expansion portion and a snap jaw, and an anti-rotation means which include formed on the cover member, first vertical ridges and first vertical grooves between the first vertical ridges; and formed on the button, second vertical ridges and second vertical grooves between the second vertical ridges, wherein the first vertical ridges are configured to be received in the second vertical grooves, and the second vertical ridges are configured to be received in the first vertical grooves.