The invention discloses a carrying water supply device for a tunnel water inrush model test and a use method thereof. The carrying water supply device comprises a carrying water supply box, wherein the carrying water supply box comprises a top plate, a bottom plate and side plates, wherein the top plate and the bottom plate are respectively welded with the side plates; water inlet holes are formed in the four corners of the top plate; a plurality of transverse rib plates and longitudinal rib plates are arranged inside the carrying water tank; the transverse rib plates and the longitudinal rib plates are connected in a crossed splicing way; a plurality of uniformly distributed water seeping holes are formed in the bottom plate; a hoisting round tube is arranged in the center inside the carrying water supply box; two exhaust holes are also formed in the top plate. The device has the advantages that the functions are diversified; the water body function and the carrying function are realized; the test simulation is more similar to the practical condition; the test results are more precise; good experiment conditions are provided for the study of the tunnel water inrush and mud inrush premonition information rule; the test reliability is higher.