The invention discloses an electrolytic tank for electrically reducing carbon dioxide. The electrolytic tank is provide with an insulating plate, the insulating plate is provide with a first insulating surface, a second insulating surface and a hollow cavity, wherein the first insulating surface and the second insulating surface are oppositely arranged, and the hollow cavity penetrates through thefirst insulating surface and the second insulating surface and is used for containing a working electrode; the peripheral wall of the insulating plate is provided with a containing hole which extends into the interior of the insulating plate and communicates with the hollow cavity, and the containing hole is internally provided with a reference electrode and is filled with a salt bridge; an anode reaction tank is formed in a first electrode surface; and a membrane is arranged between a solution electrode plate and an anode plate. According to the electrolytic tank, the distance between the working electrode and the reference electrode and the distance between the working electrode and a counter electrode are effectively reduced through the arrangement, so that the groove voltage is reduced; and the solution electrode plate is further arranged, an electrolyte cavity which penetrates through the solution electrode plate and is provided with a first open end and a second open end whichare oppositely arranged is formed in the solution electrode plate, the size of the electrolyte cavity is small, so that the use amount of an electrolyte solution is reduced, and therefore the effective concentration of a liquid-phase product is further improved, and the electrolytic tank is beneficial to analysis and detection of the CO2 electrochemical reduction reaction liquid phase product.