Correlation equation between the enthalpy of formation and the ionization potential was deduced for alkanes, based on the relationship between the heat of formation and the valence electronic energy change in the formation of a compound from its component atoms, and the relationship between the first ionization potential and the average valence electronic energy. The proposed correlation model was confirmed by taking 21 alkanes as model compounds and correlating their experimental ionization potentials to their standard enthalpies of formation, in which the expression with good correlation (correlation coefficient R is 0.9999) and lower error (standard derivation is 0.03 eV) was obtained. Using the obtained correlation expression, the ionization potentials of a set of alkanes were predicted with their experimental enthalpies of formation.