A brief summarization is made about the airworthiness regulations of windshield heating system. Based on the related aircraft, the heat transfer processes simulation of windshield which is made of multilayer structures is predicted and characteristics of two different heating modes are analyzed. The results demonstrate that the Full Heating Power Mode could make a high heating rate and then the windshield will remain a higher temperature, which is good for performance of anti-ice and defogging. Duty Ratio Heating Mode could greatly reduce the thermal shock to windshield, but it also will produce significant impact on upstream equipment because of frequent change of heating power. This article explained the airworthiness regulations was explained and the key point of the requirement on design of windshield heating system is provided for the reference of system design and airworthiness certification.