The invention provides a double-layer floor bearer of a cab. The floor bearer is composed of an upper layer a and a lower layer b. The upper layer a is of a steel structure, floors are laid, and an overall support is formed by the upper layer a and a cab steel structure 5. The lower layer b is spatially provided with pipelines 1 and circuits 2. According to the arrangement positions of the pipelines, pipeline connectors are arranged on the left side, and wire cable connectors are arranged on the right side. The lower layer b of the double-layer floor bearer of the cab is further provided with pipeline butt joint junction assemblies 3. Three cover plates 4 capable of being independently detached are arranged at the butt joint positions of the pipelines at the rear end of the double-layer floor bearer of the cab. The pipelines are covered with the cover plates 4 after being installed, internal space of the cab is isolated from the exterior, and therefore sealing and sound insulating effects are achieved. According to the double-layer floor bearer of the cab, installation of the pipelines in the cab is convenient, production efficiency is improved, overhauls and maintenance of pipeline junctions are convenient, and maintainability is improved. The sealed environment in the cab is improved, and sound insulating and noise reducing effects are achieved.