According to civil aircraft airworthiness standards, the windshield surface should avoid icing to ensure the pilot’s visual field. A reasonable heating power should be determined to prevent windshield icing. Based on the heat and mass transfer theory, a 3D thermal analysis model has been developed for civil aircraft windshield antiice system performance analysis by making use of CFD and Matlab, including antiice thermal load determination, surface temperature evaluation and critical parameter modification. Performance calculation of two typical flight cases has been given at the end of this paper.