Combined sound insulation type light steel keel

The utility model relates to the technical field of building materials, and discloses a combined sound insulation type light steel joist which comprises a first joist and a second joist, sliding grooves are formed in the two sides of the top of the first joist, sliding blocks are installed on the inner walls of the two sliding grooves in a sliding mode, and one-way racks are fixedly installed at the bottoms of the two sliding blocks. The combined sound insulation type light steel keel comprises a first keel and a second keel, the first keel is provided with two concave fixing blocks, the inner surfaces of the two concave fixing blocks are each provided with a clamping strip in a sliding mode, the bottoms of the two clamping strips are each provided with a connecting block in a rotating mode, and the bottoms of the connecting blocks are each provided with a two-way rack in a rotating mode. The sliding block is matched with the two gears through the one-way rack to drive the two-way rack to move upwards, the tw