Abstract: Focuses on the global adaptive control of a class of uncertain nonlinear systems with uncontrollable unstable linearization and unknown linear parameters. The control object is to design a robust adaptive nonlinear state feedback controller to solve the problem of global output tracking. Based on Lyapunov stability theory and using the modified adaptive power-added integrator as a tool, a nonlinear adaptive smooth-state feedback controller is proposed recursively. The proposed controller can ensure not only output tracking error sufficient small, but also all signals of the closed-loop systems globally bounded. Simulated results show that the controller is feasible and effective.