The invention relates to a worm-cam speed reduction box with a screw-free connection type and an eccentric adjusting mechanism. The worm-cam speed reduction box comprises a box body, a camshaft, a cam, a roller, a conical roller bearing, an O-shaped rubber sealing ring, a spacer ring and a lip-shaped sealing ring, wherein eccentric sleeves are arranged in bearing block holes in the left side and the right side of the box body in an interference way; the outer circle of each eccentric sleeve is provided with a boss to realize the function of axial limiting; an adjusting end cap is arranged in the left eccentric sleeve, an adjusting opening end cap is arranged in the right eccentric sleeve, the conical roller bearing is arranged between the two shaft journals of the eccentric sleeve and the camshaft, and the adjusting end cap and the adjusting opening end cap do not protrude out of the outside surface of the box body. The worm-cam speed reduction box has the advantages that the structure is simple, and the screw-free connection type is adopted; the manufacturing cost is low, the axial installation space is saved, and the like; the cam and the conical roller bearing can be wholly and axially adjusted, the gap between the roller and the cam can be indirectly eliminated, the error is reduced, and the indexing accuracy is increased.