Abstract: Based on the flight dynamic model suited to evaluate the flying qualities of a tandem helicopter,the open-loop flying qualities of a tandem helicopter at hover were studied by using military specification flying qualities of piloted vertical/short takeoff and landing(V/STOL) aircraft(MIL-F-83300) and handling qualities requirements for military helicopters(ADS-33E-PRF).According to those requirements,the dynamic response characteristics and the bandwidth were analyzed,along with the control characteristics and the attitude quickness.The interaxis coupling and the disturbance of the lateral gust were also studied.At last,the conclusions are summarized in this paper.