The invention discloses a main shaft structure of a diamond roller and grinding wheel dresser. A first shaft sleeve and a second shaft sleeve are arranged on an outer ring of a main shaft; a linkage piece, dividing an inner cavity of the second shaft sleeve into two relatively sealed cavities and capable of performing a reciprocating motion in a spline groove, is arranged in the inner cavity of the second shaft sleeve; at least one arc stopper is arranged at the end part, towards the main shaft, of the linkage piece; limiting grooves, corresponding to the arc stoppers one to one, are formed inthe end surface of the main shaft; a hydraulic oil station is arranged on an outer ring of the second shaft sleeve; the hydraulic oil station communicates with the inner cavity of the second shaft sleeve through a through hole; the orifice center of a through hole orifice formed in the inner cavity wall of the second shaft sleeve and the mouth edges of the limiting grooves on the main shaft are positioned on the same horizontal reference surface; and a hydraulic oil nozzle, communicating with the inner cavity of the second shaft sleeve, is arranged at the other side end part of the second shaft sleeve in a sealing manner. The main shaft structure of the diamond roller and grinding wheel dresser solves the technical problems of improving the working efficiency of the diamond roller and grinding wheel dresser and reducing the energy consumption, and has such advantages as high working efficiency and low energy consumption.