Faced with high failure rate and large outage losses, offshore wind farms needed to find operation faults and provided faulttolerant mechanism as soon as possible doublyfed wind generators (DFIGs) opencircuit faulttolerant projects were built based on simon decision theory, which took power quality and wind turbine reliability as typical evaluation standards. The tolerant effect was evaluated combining the example that was doublyfed wind generators rotor side converter single phase open circuit fault. The results showed that timely and effective faulttolerant mechanism could raise availability, avoid fault deterioration and reduce economic losses caused by faults in offshore wind farms.