An auxiliary siphon device for the toilet has: a hollow air container, which is bottom-opened, an abdicating groove in which a drain valve can be installed in is vertically disposed in the sidewall of the air container, said abdicating groove is communicated with the water tank; through holes for water flow are provided in the sidewall of the air container in the lower portion of the abdicating groove; a sealing bottom cover communicated with the bottom of the air container, and a drain valve installing hole is disposed in the sealing bottom cover corresponding to bottom of the abdicating groove; and a connecting tube, the bottom end of which is connected to the trapway of the toilet, and the top end of which is connected to the top of the inside of the air container.