Main structure and working processes of a two-stroke Micro Internal Combustion Swing Engine (MICSE) was introduced. A three-dimensional calculation model of the combustion chamber of the engine was established and fluid flow in the chamber was simulated coupled with sine swing using CFD software. Flow field characteristic of each process was analyzed. Mean pressure and combustion efficiency of different swing frequency was compared. The results indicate that the combustion efficiency and peak of mean pressure increases with decrease in frequency under the same inlet temperature.