The invention discloses a cooling water jacket structure for an engine. The cooling water jacket structure comprises a cylinder body water jacket arrange at the periphery of a cylinder body and a cylinder head water jacket which is arranged on a cylinder head and is provided with a side body structure and a top exhaust side structure; the width of a cylinder body water jacket torrent area is smaller than the width of two sides of the cylinder body water jacket; two sides of a side body structure torrent area of the cylinder head water jacket are communicated with the periphery through inclined sub-water jackets; the bottom of the side body structure torrent area of the cylinder head water jacket is communicated with the cylinder body water jacket torrent area; the top of the side body structure torrent area of the cylinder head water jacket is communicated with the top exhaust side structure of the cylinder head water jacket. According to the cooling water jacket structure, the cooling effect on the top exhaust side area of the cylinder head is better and the service life of the engine is prolonged.