Abstract: The processes of a droplet icing/frosting and defrosting/deicing using a dual syn-thetic jet actuator (DSJA)was experimentally studied.The temperature of a semiconductor-cooled board was reduced to -30℃,and the DSJA was started after the droplet was frozen.The processes of the droplet icing,frosting,defrosting and deicing were observed by an electron micro-scope.The experimental results show that the structure of the frost changes quickly from needle to column,and then to granule.Meanwhile,the thickness of the frost attenuates.Later on,be-cause the DSJ can enhance the heat transfer,the cone of the frozen droplet becomes flattish and the height of the frozen droplet decreases slowly.The thawed water flows downwards and freezes again.The interface area between the frozen droplet and the semiconductor-cooled board is in-creased.