The invention discloses a ball valve. The ball valve comprises a valve base, a valve cover, a valve element and a valve rod; the valve element is spherical; extension lines of the valve rod and a positioning rod do not pass through the ball center; the valve element is rotated around the positioning rod in a valve cavity; the valve element is in release contact with an outlet; a channel is connected with an inlet and the outlet; the positioning rod is matched with a positioning hole at the bottom of the valve cavity; the valve cavity is positioned in the valve base, and is connected with the outlet and the inlet; the valve base is matched with the valve cover; a stud of the valve cover is matched with a pressing nut; and the valve rod extends outside the valve cover and the pressing nut. The ball valve is simple in structure, not easy to leak, high in reliability and capable of frequently operating.