The invention discloses a capacitor clamping device. The capacitor clamping device comprises a base. The upper end of the base is provided with a lifting device. The upper end of the lifting device isfixedly connected with a supporting rod. The lower end of the supporting rod is provided with a mechanical arm. The lower end of the mechanical arm is provided with a clamping device body. The clamping device body comprises a connecting rod fixedly connected with the lower end of the mechanical arm. The outer side of the connecting rod is provided with a fixing ring. A first sliding groove is formed in the middle of the connecting rod. The side wall of the fixing ring is fixedly connected with a second driving motor. An output shaft of the second driving motor penetrates through the side walls of the fixing ring and the connecting rod in sequence. The tail end of the output shaft of the second driving motor is fixedly connected with a first threaded rod. The capacitor clamping device is reasonable in structural design, simple in operation and low in needed manual operation, greatly improves the assembly efficiency of a capacitor, and meanwhile reduces damage of the capacitor.