The combustion characteristics of intermittent ignition and flame propagation in a micro internal combustion swing engine （MICSE） were experimentally investigated on a visible two-stroke single-cylinder MICSE. In order to simulate the free swing arm motion， the swing arm was driven by a mechanical system with an electric motor. A timing system based on swing arm position was established for the spark ignition. A stable intermittent ignition of the mixture of n-butane and air in the MICSE was achieved. The ignition and flame propagation in the MICSE were observed using a high speed camera and the observed flame zone area was analyzed in detail with a Matlab program. The effect of swing frequency and premixed gas flow rate on the ignition and flame propagation was investigated. The results show that the speed of flame propagation is fast at high swing arm frequency and high premixed gas flow rate.