The invention relates to a combined defoaming and siphoning well and a combined defoaming and siphoning method. The combined defoaming and siphoning well comprises at least one siphoning well combined body, wherein the siphoning well combined body comprises a vertical well with a water inlet square culvert, a spill pit, an overflow weir, a spill pit and a water conveying square culvert; a diversion pier is arranged between the water inlet square culvert and the overflow weir at the bottom of the vertical well and is opposite to the central axis of the water outlet direction of the water inlet square culvert; the overflow weir is arranged on one side of the vertical well, and the part, adjacent to the top, of the overflow weir is provided with front weir diversion grids arrayed horizontally; at least one vertically-arranged defoaming orifice plate used for dividing the spill pit into two parts is arranged between the overflow weir in the spill pit and the outlet of the water conveying square culvert; the bottom, connected with the water outlet square culvert, of the spill pit inclines downwards. The siphoning well is provided with the diversion pier and the front weir diversion grids, so that the nappe over weir is uniform and stable; the defoaming orifice plate is used for energy dissipation and flow equalization, so that the flowing speed of waterflow after jumping is reduced; the inlet elevation of the water conveying square culvert is reduced, so that bubbles are prevented from entering the water conveying square culvert. By virtue of the measures, the bubble problem of the drainage siphoning well is solved.