A cylinder head water jacket gas-releasing device of an automobile engine comprises a cylinder head water jacket and is characterized in that a front-end penetrating hole is formed on a water jacket wall at the top of the cylinder head water jacket close to the mounting surface of a cylinder head exhaust manifold; and the front-end penetrating hole is in a sealed connection with a hollow screw plug and an exhaust connecting tube in sequence. At the front end of the cylinder head exhausting side, the penetrating hole is formed to the topmost position of the cylinder head water jacket so as to solve a of problem of releasing the air of the cylinder head water jacket when a front-mounted precursor engine is designed to a horizontal precursor engine. The exhaust connecting tube is welded on the hollow screw plug and screwed up to the front-end penetrating hole at the cylinder head water jacket side to realize sealing. Gas generated in the cylinder head water jacket passes through the front-end penetrating hole at the cylinder head water jacket side and then is exhausted via the screw plug and the exhaust connecting tube, so that the local overheating and gas erosion of the cylinder head water jacket can be avoided.