The invention discloses a movable grinding frame device of a powder coating grinding machine. The movable grinding frame device comprises a movable grinding frame, an adjusting device, a reset device and a drive system. The movable grinding frame comprises a pivot joint sleeve, a movable grinding bearing frame, a movable grinding plate and a movable connecting base. The drive system comprises a drive fixing frame, a drive damping block, a drive motor, a small drive belt wheel, a large drive belt wheel, a drive belt, a drive shaft, an eccentric sleeve and a flywheel. The drive shaft comprises an intermediate shaft body and connecting shaft bodies arranged at the two ends of the intermediate shaft body, wherein the diameter of the intermediate shaft body is larger than that of the connecting shaft bodies. The intermediate shaft body is provided with annular grooves, and a protruding ring is formed between every two adjacent annular rings. The annular grooves are sleeved with the eccentric sleeve protruding out of the protruding rings. The pivot joint sleeve is arranged on the eccentric sleeve in a sleeving manner, and an oil groove is formed between each protruding ring and the pivot joint sleeve. Better lubrication can be achieved through the structure, and the service life is prolonged.