A control mechanism of a core drilling rig includes a central rod (14) and an outer barrel (23). The central rod (14) passes through, from the rear to the front, the inner cavities of a fluid channel activation module, an outer barrel unlocking module, a flow diverging module, and a coring barrel connecting module. The coring barrel connecting module comprises a core tube connecting pipe (62), a core ring bearing (63), a bearing inner ring (64), a ball A (6211) and a ball B (6411). The core tube connecting pipe (62) is connected at the front side thereof to the coring barrel (65). The bearing inner ring (64) is inside the core tube connecting pipe (62). The core ring bearing (63) is connected to an inner wall of the outer barrel (23).