This paper described the concept of speech intelligibility in the flight test of communication system and“SINPO”rating. The common methods of evaluating the speech intelligibility in flight test and the disadvantages were introduced. Based on the research and analysis on the foreign “Rhyme List冶method, the revised “Rhyme List”adopted to the flight test of our country's communication system is established. This method defined the rank of speech intelligibility and judged the function compliance of the communication system accurately by quantitative calculation . It could provide a new kind of method for the people engaged in the field of communication system's flight test.