According to the deficiency of temperature distribution in tanks, a distributed optical fiber temperature measurement and early-warning system based on optical frequency domain reflectometer (OFDR) principle is introduced. The system is consisted of temperature measurement optical fiber, optical fiber temperature measurement main equipment and fire alarm main equipment. The scheme of optical fiber temperature measurement and early-warning based on tanks is designed, and main works for system implementation is described. The system has a good reliability and performance index, which can provide detailed space temperature distribution information and helps a lot in fire prevention and extinguishing.