The three-net-in-one fiber distribution box includes a box body and a box cover matched with the box body. The two sides of the bottom of the box body are respectively provided with fiber inlets and outlets. The top and bottom of the box body An optical fiber winding area for arranging optical fibers and a fiber storage area for storing excess optical fibers are respectively provided; the middle of the box body is provided with a fiber fusion area for fusion splicing optical fibers. The utility model is novel in structure, convenient and practical, and has high market promotion value.