The utility model discloses a camshaft case body structure, including the axle box, the one end of axle box is fixed with the flange, sets up the stiffening rib between the axle box both sides, the flange sets up the bellying, the bellying imbeds the inslot between the axle box and fixes integratively with the axle box. The utility model has the advantages that: because the flange has set up the bellying, and the bellying in advance with the flange fix integrative, and the inslot of bellying embedding axle box, consequently, flange and axle box deformation within a definite time that external force led to the fact just so can effectively be offset not on a plane to the welding seam, have improved the life of axle box.