Before a new type of civil aircraft get into serves in its airline, it must firstly pass the airworthiness certification flight test , and get the type qualification certification, the production permission certification and airworthiness certification, and then, it is permitted to get into market. There are many different types of airworthiness certification flight test for civil aircraft, in which the Negative Acceleration test is an important one for civil aircraft fuel system airworthiness qualification test. The Negative Acceleration flight test for civil aircraft is the first time attempt in domestic aviation field, this test needs excellent pilot flight skill, and is very high in risk level. In this paper, based on one civil aircraft fuel system certification flight test results, the civil aircraft negative acceleration flight test technique is studied, the "parabolic curve" method is suggested in the flight test mission. The main purpose of the paper is to introduce the problems that will likely be met in negative acceleration flight test, preparation work before the flight test, flight test method, etc, and the test results are analyzed at last.