Abstract: Due to the special condition of large oil tank farm, there are strict requirements for fire control and anti-explosion. Therefore, it is hard to excute automatic management by means of electrical signals for inspecting liquid level of a product oil tank. Introduced in the paper is a new kind of fibre inspection system with which highly accurate liquid level inspection can be performed remotely in order to reduce inspecting errors and labour intensity of manual inspection. This system consists of a level sensor allocated at the site, data display and processing by computers. Accurately processed winch wheels are installed on the mechanical parts as well as the installation of a magnetic coupling actuator to make the fibre code programing cabin be fully sealed so as to increase the accuracy and reliability of remote inspection. To guarantee reliability and long service life, infrared LED and high power photocell (PIN) are adopted. The secondary meter can be provided with direction decisive circuit so as to avoid errors due to any position movement. Through data processing by means of computers, simulation display of the present liquid level line of each tank can be available. Each tank's level, capacity, weight and remaining capacity can be calculated, displayed and printed out as well as' availabilities of automatic alarm for ligh/low level, which makes it possible to realize managerial modernization of strategic product oil storage for military defence purpose.