Built-in water-blocking pin in middle connection part of all-insulated pipe bus

The invention provides a built-in water-blocking pin in a middle connection part of an all-insulated pipe bus. The built-in water-blocking pin is arranged in a conductor tube of the middle connection part of the all-insulated pipe bus and particularly comprises a water-blocking pin body 1, airtight waterproof layers 3 and 6, water-blocking layers 4 and 5 and a boss 2, wherein the airtight waterproof layers 3 and 6 are made of rubber seal rings and are arranged in the grooves, close to two ends, of the water-blocking pin body 1 to form a first waterproof and moisture-proof layer; the water-blocking layers 4 and 5 are formed by winding water-blocking tapes and are located in the grooves close to the boss 2 to form a second waterproof and moisture-proof layer; when the first waterproof and moisture-proof layer is damaged and loses the protection effect, the water-blocking tapes quickly absorb water to expand, and seal a water vapor channel to form dual isolation and protection effects, in other words, the connec