The Fiber Optic Splice Closure is a connecting part that connects two or more optical cables together and has protective components. It is a must-have in the construction of optical cable lines and is one of the most important devices. The quality of the fiber optic splice closure directly affects the quality of the cable line and the service life of the cable line, especially the sealing performance of the fiber optic splice closure. The sealing groove used in the fiber optic splice closure used in today's line is a flat groove, which is filled by a sealing strip, and the box cover of the joint box is crimped and sealed, and the sealing performance is not good, and the terminal point loss is increased in severe cases. The utility model relates to a high-sealing type 48-core fiber optic splice closure, which comprises a box body and a box cover, which are connected by bolts, wherein the upper end surface of the body wall of the box body is provided with a continuous sealing groove, the sealing groove a bottom of the bottom is provided with a m-shaped convex line, a sealing strip is disposed in the sealing groove, and the connecting bolt passes through the box body and the lid to make the lower end surface of the sealing strip and the convex line of the rice-shaped convex line Interlaced and intimate contact; an optical fiber cable inlet and outlet hole is disposed on one end of the body of the casing, and one end of the bottom surface of the inner cavity of the casing is provided with a cable crimping device and a cable reinforcement fixing device, and the bottom surface of the inner cavity of the casing The middle portion is provided with a fiber fusion splice tray; the m-shaped convex line is continuously or intermittently disposed, and the m-shaped convex line is integrally cast with the box body.