In this paper, a practical method to design a robust controller for pressure of boiler in Mashhad Power plant using Quantitative Feedback Theory (QFT) is proposed. In reality fuel flow, air flow and pressure of boiler are three dependent parameters which must control in every power plant. The boiler pressure system has uncertain mathematical model. Uncertainties in mentioned model are caused by lack of knowledge about the dynamics of the system, pay load changes, air flow. Thus, application of robust control methods for high precise control of pressure is inevitable. In the first step plant is converted into a group of linear uncertain plants. Then, a controller is designed for tracking problem and disturbance rejection. Finally, nonlinear simulation has been carried out which indicates successful design of controllers and pre-filters. The research demonstrates that applying the proposed technique successfully overcomes obstacles for robust control of pressure of the Power plant.