The problem of global robust output regulation for uncertain nonlinear systems with linear external systems is studied when the control direction is unknown.It is assumed that the system and high-frequency gain symbols are unknown, and the unknown parameters can be arbitrarily large, which bring a challenge to the design of the controller.In order to solve this problem, firstly, coordinate transformation is conducted to calculate the new state equation.Then, by using Nussbaum dynamic gain technology, the adaptive control method and the internal model principle, the robust output regulation problem is transformed into the robust stability problem, and a dynamic output feedback controller is designed.Finally, Lyapunovs derivative is made negative definite by using the designed dynamic output feedback controller.In this way, the problem of global robust output regulation of the nonlinear output feedback system is solved theoretically.The effectiveness of the proposed adaptive controller is illustrated by an example.