Abstract: This paper studied the problem of robust active queue management (AQM) controller design in Internet congestion control. The problem was first reduced to a robust stabilization one based on the linear model of transmission control protocol (TCP) and the AQM design objectives. A sufficient existence condition of the output feedback controller was then obtained and its design method was provided using linear matrix inequality (LMI) approach. Finally, a design example was given and the simulation was performed. The simulated results show that the proposed controller is feasible and valid for it possesses not only robustness for all the network parameters but fast settling process.