Abstract: A robust fault detection scheme is proposed for a class of networked control systems(NCSs) with the unknown inputs and modeling uncertainties.A fault detection filter is designed by using H_∞ control theory.The uncertain NCS with both network transmission delay and data dropout is modeled as a continuous-time system with two additive delay components in the state by employing an input delay approach.A new result on H_∞ performance of the continuous-time system is derived by exploiting a Lyapunov-Krasovskii functional.And based on it,the existence condition of the robust fault detection filter for the uncertain NCS is obtained,which is dependent on the size of the delay.Finally,a numerical example is given to demonstrate the validity of the proposed approach.