The present disclosure discloses an electric-machine housing structure, wherein the electric-machine housing structure includes an outer housing, an inner housing and a plurality of intermediate pieces provided between the outer housing and the inner housing; and the intermediate pieces are overall hollow arcuate structures or annular structures, upper surfaces and lower surfaces of the intermediate pieces are provided with a plurality of protrusions and/or grooves, the protrusions and/or grooves of the upper surfaces match with and are fixed to grooves and/or protrusions on an inner circumferential face of the outer housing, and the protrusions and/or grooves of the lower surfaces match with and are fixed to grooves and/or protrusions on an outer circumferential face of the inner housing.