This paper is concerned with the event-triggered H_∞ fault detection problem for discrete-time networked control systems with unreliable communication links. Firstly, an event-triggered mechanism is proposed to determine whether the sampled data is transmitted to the network in order to save network resources. Then, a Bernoulli process is employed to model the phenomenon for the packet losses. Considering the above constraints, a networked control system model is established, which can simultaneously describe the event triggering strategy, data losses, distributed delay and time-varying delay. The sufficient conditions for the fault detection filter are obtained using the Lyapunov stability theory and the linear matrix inequality method. Finally, the numerical simulation is conducted to prove that the fault detection filter under the event-triggered mechanism not only saves networked resources, but also effectively detects system fault information.