The invention discloses a multifunctional water tank and a manufacturing method thereof. The multifunctional water tank comprises a frame, a bottom plate and a folding strip, wherein the folding strip is arranged on the outer side of the open end of the frame; the bottom plate is obliquely arranged on the inner side of the closed end of the frame; an annular dredging groove is formed between the frame and the bottom plate; and flow guide and dry-wet separation of the water tank are realized through the annular dredging groove. The multifunctional water tank has the functions of flow guide and dry-wet separation, water in the water tank can be quickly injected into a drain hole, cleaning is convenient, cleaned vegetables and fruits can be drained conveniently, residual accumulation of water at the bottom of the water tank is reduced, breeding of bacteria is reduced, a knife sharpener, a draining basket and a knife rest can be placed on the water tank conveniently, and modular combination is realized. The manufacturing method is simple in step, the frame and the bottom plate are machined respectively, then the machined frame and the machined bottom plate are welded and fixed, the strength and stability of the whole water tank are effectively improved, the thickness of the frame and the thickness of the bottom plate are uniform, and the defective rate is reduced.