The electronic structures of 17 perchlorofiuoroolefins and perfluoroolefins were calculated using the MNDO method. Based on these calculations combined with the perturbation theory, a good structure‐reactivity relationship of perchlorofluoroolefins has been established. In the case of internal olefins, the direction of nucleophilic attack is governed not only by the perturbation energy of the ground state, but also by the stability of the anionic intermediate and the activation energy of the reaction.