This paper presents a fault diagnosis method for neutral grounding three-phase bridge type solid-state fault currentlimiter（SSFCL）. Simulation studies show that based on monitoring and analysis of current of DC reactor and two free-wheelingdiodes for the bridge， different type faults of bridge-arm breaking and through can be effectively distinguished so as toimplement diagnosis of bridge fault type. With current waveforms of the DC reactor and two free-wheeling diodes and theirFourier analysis， the DC， fundamental and second harmonic components can be calculated to locate fault bridge-arm. Thismethod has many advantages， such as small monitoring amount， obviousness of fault characteristic， the simple criterion， etc.It is conducive to realize on-line monitoring and fault diagnosis for arms of rectifier bridge of SSFCL.