According　to　the　status　of　rotorcraft　and　mechanical　structure　of　three-rotor,　this　paper　analyzed　the　torque　of　a　three-rotor　aircraft　and　established　its　mathematical　model.　Active　disturbance　rejection　control　(ADRC)　was　applied　to　the　control　of　attitude.　To　investigate　the　performance　between　ADRC　and　PID,　series　of　comparative　experiments　were　carried　out.　Results　show　that　different　sizes　of　step　signal　can　be　adjusted　by　different　parameters　in　ADRC,　and　ADRC　is　more　effective　and　rapid　than　PID.　ADRC　can　not　only　keep　the　general　framework　and　structure　of　PID,　but　also　has　better　performance　on　filtering　and　robustness,　which　has　important　guiding　significance　in　engineering　and　experiments.　©　2016,　Editorial　Department　of　Journal　of　Beijing　University　of　Technology.　All　right　reserved.