Disclosed is ball valve with automatic safety exhaust function, which is suitable for working environments in high pressure applications, such as up to 600 psi of water, oil, and gas. The ball valve includes a valve body, cap, ball with a vent hole, stem, a built-in vent needle valve, and seals. When the valve is in the closed position, the built-in needle valve is in the open state. The downstream gas enters the bottom of the valve cavity from the exhaust hole on the ball and exits the valve body through the needle valve hole. When the ball valve is in the open position, the built-in needle valve is in the closed state. The built-in needle valve design ensures that under high-pressure use (open state), the gas will not leak out of the valve body.