How to detect and isolate earth-faulty section is an important subject to realize distribution automation in ineffectively grounded systems. Traditional single fault-detection method using only some parts of fault information has poor reliability. Fuzzy sets theory is introduced and applied in fault line detection to make the fusion of multi-fault information, and therefore improves the detecting performance greatly. The realization of software and hardware for the fusion strategy is also introduced. Dynamic mould laboratory emulation results show that the fusion strategy exhibits excellent property over the existing criteria.