Optical fiber connection is one of the most common and important links in optical cable engineering. The selection of optical fiber connection technology and connection box will affect the attenuation of optical fiber and the service life of optical cable. The optical cable that was put into operation early in the system will increase with the service life. The attenuation index of the optical fiber has changed abnormally. Most of the failures of the optical fiber appear on the fiber optic splice closure. The fiber optic splice closure is an important component that affects the attenuation performance of the optical fiber. The common failures of fiber optic splice closure in recent years, from the point of view of the failure of the fiber optic splice closure in the system, is nothing more than deformation and water seepage. The deformation of the fiber optic splice closure is mostly due to the poor operating environment, such as the annual run at the concentration of acid and alkali The corrosive deformation caused by the large air, the mechanical deformation caused by the impact of external forces, etc., this kind of failure is not a lot, and it is common that the core is caused by water seepage (water vapor) caused by the sealing failure of the fiber optic splice closure. The failure, and the deformation of the fiber optic splice closure will eventually lead to the destruction of the sealing of the fiber optic splice closure. The damage of the fiber optic splice closure is caused by many reasons. Common reasons include the following: The material and sealing performance of the Inline Closure largely depend on the quality of the fiber splice cassette housing material. Some low cost and inferior splice cassette materials are made of recycled plastics and other inexpensive materials, and its anti-corrosion performance and The mechanical strength is very poor, the general operation will be a problem for several years, this type of problem is still less in the system.