The utility model relates to a water collecting apparatus of a water slag product bin. The water collecting apparatus comprises a water collecting device, a water receiving pipe, a water guiding pipe and a connection water pipe. The utility model is characterized in that two water collecting gutters (10) are arranged on both sides of the water collecting device (1) respectively, the water collecting device can move horizontally to collect the water which flows out from a discharge valve of the product bin. The water collecting apparatus has the advantages that pulp water which flows out from the discharge valve of the product bin can be collected in time; thus on-site water pollution is controlled, and hidden danger is eliminated; at the same time, the pulp water discharged from the discharge valve of the product bin can be fed back to the water collecting tank and converged into slag-flushing water circulation, and water resources are saved.