Abstract: The fire alarm device of oil storage tank is of great significance to the safe operation of large oil depots. At present, fire alarm systems with the optical fiber grating temperature sensing device as the main part are faced with high false alarm rate and inconvenient repair and maintenance. In order to solve these problems, a wireless temperature sensing probe was innovatively installed at the secondary seal ring of the floating disc of floating roof tank. By virtue of the wireless transmission technology, the measured temperature data was real-time uploaded to the principal computer for monitoring, and the wireless tank fire alarm system was established to achieve the linkage of tank top temperature detection with fire alarm. It is verified by extensive testing and long-term trial that the wireless tank fire alarm system is advantageous with accurate measurement, single-point display, convenient installation, simple maintenance, strong stability and reliability. Therefore, it is worth further researching and application.