The invention discloses an aligning type composite centre pair of a computer numerical control roll grinder tool. The aligning type composite centre pair comprises a reference base, a centre block and ejection blocks; three directions, every two of which are mutually perpendicular, are set as the direction x, the direction y and the direction z respectively; the axial direction of the reference base is the direction z, the centre block stops moving in the direction z and can be glidingly positioned on the reference base radially, and at least one group of the ejection blocks can be movably positioned on the surface of the reference base in the directions x and y respectively and are fixedly positioned with side walls of the centre block in the two mutually perpendicular directions respectively. The centre block is ejected by the ejection blocks to move on the reference base in the two mutually perpendicular directions, accordingly, fine adjustment of the axis position of the centre block is realized, and concentricity of the centre block and outer circles of two bearing retainers on a spindle is realized. The aligning type composite centre pair is simple in structure and convenient to operate, can be used for grinding the outer circles of the two bearing retainers on the grinding spindle, an outer circle of a cone meeting the grinding wheel mount reference being 1:30, an outer circle of a cone meeting the mount reference, namely, 1:5, of a grinding wheel on a grinding head taper sleeve and the like, and is high in universality and convenient to process and manufacture.