Flight testing is characterized by tight time constraints, high risks, and strong technical comprehensiveness. Both domestic and international civil aircraft flight test organizations consider flight test simulator as an important mean to ensure flight test safety and improve flight test efficiency. This article introduces the characteristics of flight test simulator in terms of task undertaking, flight test scenario simulation capabilities, and rapid configuration changes. Incorporating the application scenarios of a certain type of civil aircraft flight testing, this article elaborates on the roles played by flight test simulator in verifying flight test outlines, training flight test crews, reducing potential risks, and innovating flight test mode.