Airports with Type II ILS is the precondition of CAT II ILS flight test. Since domestic airports with Category II operation condition are all large hub airports, many restrictions will greatly affect the efficiency of flight test. In order to increase the airports selection margin, and accelerate the test process, this paper firstly proposed a new method of carrying out CAT II ILS flight test by Type I ILS in domestic. And the feasibility of this method is analyzed in detail from the aspects of airworthiness regulations and technical requirements. The research results showed that this new method can meet the requirements of airworthiness certification and it is feasible. It’s an effective flight test method that can be applied to most airports with Category I operation condition in domestic.