The water quantity of a boiler drum is regarded as an primary factor for ensuring the safety of boiler. Once a drum is short of water, the consequence of a boiler explosion caused thereby is dreadful to contemplate; especially for a steam boiler of high or medium pressure, because it will affect the bolumetric watersteam ratio, furthermore affecting the working pressure. Therefore it is an important task for a boiler operator to keep close watch over boiler level. But a boiler drum is normally located 10m to 150m away from its control room and 20m to 60m above the ground, it is not easy to check directly the bicolour levelmeter on a drum. The electric sensor for observation of water level we are using nowadays is proved not reliable due to long-term service in high temperature environment. Up to now, no such a device which can ensure a direct observation of boiler drum water level from control room is availabe. In this case, the author has, through one year's research, developed by using optical fibre technology an optical fibre remote monitoring system for boiler water level (its working principle as per Fig,1).