The invention relates to a clamping shell type main shaft coupling of a ring spinning frame. The clamping shell type main shaft coupling of the ring spinning frame comprises a clamping shell, a key slot-carried clamping shell, internal hexagonal screws, nuts and gaskets; the clamping shell and the key slot-carried clamping shell form a hollow cylinder; four gap grooves, in position symmetry, are formed on the outer surface of the clamping shell along two sides of the axis of the clamping shell; four gap grooves, corresponding to the outer surface of the clamping shell, are arranged on the outer surface of the key slot-carried clamping shell along two sides of the axis of the key slot-carried clamping shell; the gap grooves are set as widths and radians capable of rotating when placing theinternal hexagonal screws and incapable of rotating when placing the nuts; and the internal hexagonal screws are connected with the nuts through the gaskets. The clamping shell type main shaft coupling greatly reduces the rotating inertia, is suitable for high-speed equipment operation and low in energy consumption, reduces the mounting time and the cost, and is reliable in structure, high in bearing capacity, long in service life and suitable for an ultralong vehicle.