A new fault monitoring mechanism for optical burst switching(OBS) networks is propoed pertinent to that a lot of false alarms will be generated in OBS circumstance if traditional optical network monitoring method is only used.Using data channel information contained in the burst header packet of OBS,the mechanism can control the alarm-permitting time and discard the redundant alarming information.So it can provide reliable alarming information for fault location module,and effectively decrease the number of false alarms while there is almost no missing alarm.Simulation results validate that the shorter time the fault detection needs,the more false alarms are filtered.