The invention belongs to the technical field of machinery, and particularly relates to a self-centering self-locking chuck of a grinding machine. The self-centering self-locking chuck of the grinding machine comprises an outer shell and an ejector pin, wherein the outer shell is provided with a cavity; the ejector pin penetrates in the outer shell; an inner shell is inserted in the outer shell; the outer shell and the inner shell can rotate freely; an annular boss is arranged on the upper end surface of the inner shell; three cores for clamping a workpiece are uniformly arranged on the upper circumference of the upper end surface of the annular boss; heads of the cores are hinged to the annular boss; a preloaded spring is arranged at the tail of each core; a shaft sleeve which is connected with the ejector pin in a sleeving manner is arranged in the inner shell; and the shaft sleeve freely rotates in the same direction only relative to the inner shell. The self-centering self-locking chuck of the grinding machine is simple in structure.