In this paper, the differences of flight dynamics characteristics between gyroplane and helicopter are discussed firstly. Based on force analysis of an unmanned gyroplane, a nonlinear model is established and an autonomic takeoff mthod is proposed as well, in which the longitudinal and lateral control are kept in balance with ground force, attitude and lateral skidding feedback so that the unmanned gyroplane can climb up smoothly without ground constraints. The strategy is verified successfully during the flight test of an unmanned gyroplane, which provides useful experience and application value of the proposed method for unmanned gyroplane autonomous takeoff technology, also demonstrates the effectiveness of the proposed approach.