Abstract: Disclosed is an intake swirl enhancing structure for internal combustion engine mainly including a guide shaft and several guide interfaces radially extending from the guide shaft to split a space into several intake passages. Each of the guide interfaces has a curved outer corner near an outlet end of the intake passages to swirl gas flowing through and out each intake passage, so that the gas enters a cylinder of the engine and forms a turbulent swirl in the cylinder. The intake swirl enhancing structure may be directly set in an intake manifold or an intake port for use without the need of modifying the existing engine design. Enhanced swirls produced by the intake swirl enhancing structure result in faster and steadier burning of mixture in the engine. When the structure is employed in the lean mixture burning, reduced fuel consumption and minimized environmental pollution can be achieved.