With the increasing of complexity of the battlefield environment and fight tasks, operations conducted by either the helicopter or Unmanned Aerial Vehicle (UAV) solely have its own limitations. In order to realize the mixed-formation operation of helicopters and UAVs, it is necessary to study the helicopter-UAV cooperative test technology, so as to provide a theoretical basis and experimental data support. Based on the cooperative combat tasks of helicopters and UAVs, and taking the verification of the second-stage helicopter-UAV cooperative capability as the objective, we constructed the helicopter-UAV relay communication profile. From the top to the bottom, the profile was decomposed by tasks and test points. The key technologies during the relay-communication testing process were analyzed. At last, typical experimental scenes were chosen to carry out the test flight and verify the helicopter-UAV relay communication. The information exchange between the helicopter and the ground command center was realized through UAV communication relay. The performance of the communication relay met the operational requirements. The flight test verification of the second-stage cooperation of helicopters with UAVs was implemented, which can be taken as a reference for the subsequent third-stage test flights in the future.