The invention discloses an overflowing ball valve. The overflowing ball valve comprises a valve body, a ball body, a valve rod, a connecting valve cylinder, an overflow valve clack, a transmission valve rod and a valve rod operation mechanism, wherein the connecting valve cylinder is arranged a fluid inlet side of the valve body, an inner cylinder hole communicated with the fluid inlet of the valve is formed in the connecting valve cylinder, the transmission valve rod is installed in the connecting valve cylinder in a sliding mode, the overflowing valve clack is installed at the outer side end of the transmission valve rod in a sliding mode, a limiting locking part is arranged on the transmission valve rod, the overflowing valve clack is matched with the end of the connecting valve cylinder in a sealing mode, and an overflowing compression spring is arranged between the overflowing valve clack and the transmission valve rod. The valve rod operation mechanism is installed on the connecting valve cylinder and can drive the transmission rod to slide inwards and outwards to open or close the overflowing valve clack. The overflowing ball valve can limit the flow speed of fluid when opened and has an overflowing protection function. The sealing performance of the ball valve is improved to some extent, and the leakage probability of the fluid is reduced.