The invention discloses a hot water supply device based on a coal furnace. The hot water supply device comprises a heat supply unit and a hot water storage unit; the heat supply unit is a honeycomb briquette furnace which consists of a furnace body, a hearth and a furnace grate; the furnace grate is provided with a plurality of gaps which allow honeycomb briquette slag to pass through; the upper and lower ends of the furnace body are each provided with a through hole for accommodating and pulling a furnace drawer; the front and rear ends of each furnace drawer are separately provided with twocoal storage boxes which are equivalent to the honeycomb briquettes in diameter; the hot water storage unit consists of a hot water storage tank, a water inlet and a water outlet; and a heat collectoris arranged inside the hot water storage tank. The hot water supply device disclosed by the invention is used for supplying hot water by utilizing afterheat of the honeycomb briquettes, saves energy,protects the environment, increases the utilization rate of resources, can provide convenience for replacing the honeycomb briquettes, is simple to operate and is not prone to burning and scalding abriquette replacing person.