The plug valve is a rotary valve in the shape of a closing member or a plunger. By rotating 90°, the channel port on the valve plug is the same as or separated from the channel port on the valve body, so as to realize the opening or closing of a valve. The shape of the plug of the plug valve can be cylindrical or conical. In cylindrical plugs, the passages are generally rectangular. In conical plugs, the passages are trapezoidal.