Through treating the high-order subsystem as a nonlinear uncertainty, this paper converts a high-order hybrid adaptive system to a lower-order, sampled-data, indirect adaptive control problem through a special transformation, and analyzes its stability via the framework for stabilization of sampled-data systems based on its approximate discrete-time models. Therefore, a stability analysis framework for the adaptive control based on the characteristic model is proposed, and it is helpful to analyze the stability of system which applies the lower-order adaptive robust controller to control the high-order system.