The problem of finite-frequency fault detection (FD) for a class of nonlinear systems with Lipschitz nonlinearities, unknown faults, and bounded disturbances is explored. To start with, a finite-frequency FD filter based on an adaptive eventtriggered mechanism is put forward, and the augmented filter system is transformed into a linear parameter varying (LPV) system by the reconstructed Lipschitz property. Then, two sufficient conditions for the LPV system to be asymptotically stable with a full-frequency H_∞ disturbance attenuation index bound and a H_ finite-frequency- fault-sensitive index bound are derived. Next, the obtained sufficient conditions are sorted into numerically solvable linear matrix inequalities to obtain the desired FD filter parameters. Finally, an illustrative example is carried out to demonstrate the advantages of the presented FD scheme.