The invention discloses a water-cooling hearth plate of a petroleum coke tank-type calcining furnace, and belongs to the technical field of petroleum coke tank-type calcining furnaces. The water-cooling hearth plate of the petroleum coke tank-type calcining furnace comprises an upper flat plate (1) and a lower flange plate (2), wherein the upper flat plate (1) is fixedly connected with the lower flange plate (2) through an annular connecting plate (3). The water-cooling hearth plate of the petroleum coke tank-type calcining furnace is characterized in that a flange cooling pipeline (6) is formed inside the lower flange plate (2), an upper flat plate cooling pipeline (9) is arranged inside the upper flat plate (1), a connecting plate cooling pipe (5) is arranged inside the connecting plate (3), the two ends of the connecting plate cooling pipeline (5) are communicated with the flange cooling pipeline (6) and the upper flat plate cooling pipeline (9) respectively, the flange cooling pipeline (6) is communicated with a water inlet pipeline (7), the upper flat plate cooling pipeline (9) is communicated with a water outlet pipeline (8), and a cooling water circulation pipeline is formed. The water-cooling hearth plate of the petroleum coke tank-type calcining furnace has the advantages of recycling the heat of the hearth plate, lowering the temperature of the hearth plate, improving the surrounding work environment, prolonging the service life of the calcining furnace and the service life of equipment around, and the like.