The invention discloses a sacrificial anode consumption monitoring device and a monitoring method. The monitoring device comprises an iron core and a sacrificial anode, wherein the iron core penetrates through the sacrificial anode; a plurality of protective casings are arranged along the length direction of the iron core; a metal core is arranged in each protective casing; a transverse through hole is formed in the side face of each protective casing; the height of the transverse through holes in all the protective casing is sequentially reduced; the protective casing and the sacrificial anode are poured into a whole; and wires connected to the metal cores are led out from the upward sides of the protective casings after pouring and molding. According to the sacrificial anode consumptionmonitoring device and the monitoring method, through the electric potential signals received by an electric potential monitoring device between the metal cores at different positions and a protected object, the specific loss depth of the sacrificial anode can be judged, and the periodic consumption condition of the sacrificial anode can be effectively monitored.