In this paper we study the fault tolerant control (FTC) problem on wireless networked control systems (WNCSs) which have been aware of a bright and broad prospect and taken as a development trend of automation industry. We aim at finding an FTC strategy which makes the WNCSs satisfy a quadratic cost function. The FTC law is designed to be related with the system state and the fault. Considering the system state and the fault may be physically unaccessible in the actual control process, an estimation scheme is proposed to estimate the system state and fault simultaneously. Finally, an experimental application is presented to demonstrate the effectiveness of the proposed method.