By employing systematism and structural characteristics of Backstepping method, this paper studied the robust decentralized adaptive control for a class of uncertain nonlinear interconnected systems with nonlinear parameter. Firstly,under more intuitionistic and more common assumptions, and according to the structural characteristics of the systems,the controller and adaptive laws were proposed based on backstepping,and the controller and adaptive laws of the subsystems just depend on the states information from the subsystems itself,which is called decentralized control. Then it is proved that the designed controller and the adaptive laws make the states of systems controlled, and the parameter estimate errors are uniformly ultimately bounded by Lyapunov theroy. And finally the simulation of an example shows the validity of the control algorithm .