Propanol, n-decane, and diesel droplets were selected as experimental samples to study combustion behavior of fuel droplets in a vertical electric field under gravity. A high speed camera was used to measure the combustion flame and droplet size, with laser-induced incandescence (LII) applied to determining soot volume fractions. The results show that the flame height of each fuel increases with increasing electrodes voltage, while the flame width decreases with increasing electrodes voltage. Propanol droplet combustion does not produce soot, with n-decane and diesel flame soot volume fraction decreasing with increasing electrodes voltage. Burning rate constants increase with increasing electrodes voltage with the maximum burning rate constant increasing by 9%, 20%, and 30% for propanol, decane, and diesel, respectively. Analyses show that electric field stretching on the flame induces soot formation suppression and promotes soot oxidation, reducing soot generation and weakening soot external radiation heat transfer, so as to promote fuel combustion.