The invention relates to a combined sealing ball valve. The combined sealing ball valve comprises a valve body, a first valve seat, a first valve clack, a valve ball and a valve stem, wherein the first valve clack is moved on the valve ball in a stretchable mode, and the first valve clack is engaged with the first valve seat when a ball valve is closed; the first valve clack is provided with a first pressure release valve, the valve ball is provided with a first driving ring, and the first driving ring drives the first valve clack and the first pressure release valve; in the closing process ofthe ball valve, when the first valve clack and the first valve seat are engaged, the first pressure release valve is closed; and in the opening process of the ball valve, when the first pressure release valve is opened, the first valve clack and the first valve seat are separated from each other. The pressure relief valve is arranged in the forced sealing ball valve, so that the operation resistance of the ball valve used in a pressure pipeline is reduced, and the abrasion of a transmission mechanism is reduced; and the operation performance of the forced sealing ball valve can be remarkablyimproved, the service life is prolonged.