This paper presents a Backstepping-L1 adaptive control method aimed at the problems that there are outside interferences such as crosswind, etc., and nonmodeling dynamic uncertainties exist in aircraft itself in the process of flight for attitude control of multirotors. Firstly, according to the kinematics and dynamics equations of multirotors, the paper designs a Backstepping control law by a Lyapunov function under no consideration of uncertainties to realize a fast, accurate and stable control target. Then, under consideration of the influence of uncertainties, the paper introduces adaptive law and state predictor into the system on the basis of Backstepping controller. With the augmentations of adaptive law and state predictor, the real time estimation of uncertainties and online state prediction are realized. A L1 adaptive controller is designed to compensate the influence of uncertainties and make the system robustness and fault tolerant. And its stability analysis is realized by introducing a stable reference system. The analysis result shows that the state predictor, adaptive law and control law can ensure the system stable. MATLAB simulator is provided to demonstrate the performance of the presented control scheme.