Abstract: An outdoor optical fiber splicing box, a cable storage structure is fixed at the bottom of the inner cavity, a plurality of wiring structures are stacked on the upper side of the cable storage structure, and two sides of the wiring structure are provided with a multi-fiber supporting mechanism and a single-fiber supporting mechanism, which are fixed at the bottom of the inner cavity. The single-fiber and multi-fiber supporting mechanisms are all arranged on the side of the wiring structure. The box body is provided with a first and a second cable inlet/outlets, and the first cable inlet/outlet is provided with a single optical fiber waterproof structure. The second cable inlet/outlet is provided with a multi-fiber waterproof structure, and the waterproof effect is good. At the same time, the single-fiber and multi-fiber supporting mechanisms can protect the optical fiber cable from vibration, impact, cable stretching, and twisting.