An auxiliary control method and an auxiliary control system for an unmanned aerial vehicle (UAV) are provided. The auxiliary control method for the UAV includes steps of: based on a flight attitude and a flight speed of the UAV, predicting a flight path of the UAV in a scheduled time; and providing information about the flight path of the UAV in the scheduled time to an operator of the UAV. The auxiliary control method and system for the UAV provided by the present invention are able to provide the information about the flight path of the UAV in the scheduled time to the operator of the UAV, so as to help the operator of the UAV make a control decision for the UAV.