In this research, a combination of reactive force field (ReaxFF) and electron force field (eFF) molecular dynamics (MD) simulations is constructed to reveal the fundamental mechanisms for the influence of the electric field on ethanol oxidation reactions at atomic and subatomic scales. In total, 21 ReaxFF MD simulations and 35 eFF MD simulations have been conducted. ReaxFF MD results indicate that the ethanol oxidation reaction is a two-stage process where the electric field plays varied roles in each stage. The first stage features the decomposition of ethanol molecules, in which the electric field influences the decomposition reaction rate by changing the kinetic energy of carbon-containing molecules/radicals on the order of 100–1000 kJ/mol and altering the molecular conformation and thereby the bond dissociation energy. At the second stage where oxygen molecules participate in the reaction, the electric field affects reactions by modifying the reaction pathways. The application of the eFF MD simulations, for the first time, extends our understanding of the electric field effects on ethanol oxidation reaction to subatomic scales. The results indicate that the electric field modifies the electron energy on the order of 10–100 kJ/mol. The present study also offers interpretation of previous findings on electric field effects on reaction pathways and fluorescence experimental observations, and provides support for both “ionic wind” and chemistry-driven hypotheses. This research provides unprecedented insight into reactions aided by the electric field, which potentially can facilitate the design of realistic field-assisted combustion systems.