Taper roller bearing can be dismantled, whose inner ring, assembly part made by rollers and cage, outer rings can be separately assembled. the amendatory contact line in the contact place of rollers and grooves can reduce the concentration of stress. Taper roller bearings, which can bear not only heavy axial but also heavy radial loading capacity, need to be used together with a symmetrically assembled one to transfer the opposite axial loading because of its just ability of transferring the unilateral axial loading capacity.