The invention discloses a system for measuring the explosion limit of liquid fuel vapor. The system comprises an explosion bin (1), a computer, a main control system, a first vacuum pumping device (7) connected with the main control system, a gas circulating device (8), a liquid fuel vapor supply device (4), a dry air supply device (5) and an ignition device, wherein the liquid fuel vapor supply device (4), the dry air supply device (5) and the first vacuum pumping device (7) are communicated with the explosion bin (1); an ignition electrode (6) and an explosion bin pressure sensing device are mounted in the explosion bin (1); the ignition electrode (6) is connected with the ignition device; the explosion bin pressure sensing device is connected with the main control system; the main control system is connected with the computer; and the computer is communicated with the explosion bin (1). The invention also provides a method for measuring the explosion limit of the liquid fuel vapor. The system for measuring the explosion limit of the liquid fuel vapor has the advantages being safe, reliable and capable of accurately measuring.