Abstract: Minimum electrostactic ignition energy, the minimum energy for igniting fuel gas under sensitive electrostatic firing conditions, is usually measured by the method of capacitance spark discharge. First, measure the ignition energy values under certain firing capacitance and different LPG concentrations, and fit them into a curve to obtain the sensitive concentration. Then, measure the ignition energy values under sensitive LPG concentration but different firing capacitances, and fit them into a curve to obtain the minimum firing energy-LPG's minimum electrostatic ignition energy. The minimum electrostatic ignition energy, sensitive concentration and sensitive capacitance measured under ambient temperature and atmospheric pressure are(0.31±0. 05)mJ, 3.9 % and 4.2 pF respectively. For better understanding the experimental principle, different mechanisms under sensitive conditions are discussed, sensitive capacitance, sensitive electrode and sensitive gap are analised using the principle of spark discharge, and sensitive concentration explained qualitatively with the theory of gas self-diffusion.