Abstract: Several defects existed in temperature induction cable, fiber-grating temperature induction alarm system and fire pre-alarm monitoring system installed in large-scale floating-roof oil tank are analyzed and problems arising during oil tanks' fire fighting are studied. It is pointed out that for the extinguishing system during fire fighting, there is a blind area for foam system of tank top, the fire control capacity for ground fixed and/or moving extinguishing system are lower, which are major failure factors to extinguish fire. In the light of field fire of oil tank, improvement measures to enhance fire fighting effectiveness are provided.