Helicopter inlet icing up will seriously threaten the flight safety. Probably reduced power or increased load of engine， so Anti-icing flight test is especially important，Based on the research of military standards and airworthiness ,and the method of foreign ground and flight anti-icing test, this paper design a new test method of helicopter inlet anti icing system that has been verified by the icing test. The test result show that the method is insufficient, which is significant for the later helicopter inlet icing test.