The invention discloses a special fixture for large gear laser cladding of a coal mining machine, relates to a special fixture, and solves the problem of no special fixture for large gear laser cladding of the coal mining machine at present. One end surface of an indexing device connecting disc is fixedly mounted at the head part of a large gear dowel pin; a clamping end cover and the large gear dowel pin are coaxially and horizontally arranged; fixture support frames are respectively mounted at the lower end of the clamping end cover and the lower end of the indexing device connecting disc; a worktable connecting disc is connected between the two fixture support frames; one end surface of an index plate is fixedly mounted on the other end surface of the indexing device connecting disc; the large gear dowel pin, the indexing device connecting disc and the index plate are coaxially arranged; index pins are uniformly distributed on the other end surface of the index plate in the peripheral direction; a handle bracket is fixedly mounted at the lower part of the indexing device connecting disc; a handle is mounted on the handle bracket; and an index cam is fixedly mounted on the handle, and is engaged with the index pins of the index plate. The special fixture is used for the large gear laser cladding of the coal mining machine.