Abstract: A novel adaptive path following controller was presented for a miniature autonomous helicopter with uncertain inertial parameters and external disturbance. It was implemented by using dual-loop structure, including an outer-loop for path following and an inner-loop for attitude control. The outer-loop controlled the attitude angles and lift forces to track the expected path and velocity, and the inner-loop was designed as a attitude controller based on L₁ adaptive controller. The uncertain inertial parameters were and external disturbance were also compensated online by using parameter adaptive update laws in the inner-loop. The stability analysis for the inner- and outer-loop was provided separately and the closed-loop stability analysis was given on the basis of time-scale separation assumption. Finally, a simulation and a flight test were carried out. The results demonstrate that the feasibility and performance of the proposed controller.