A new reaction molecule model has been proposed for analyzing ignition process in supersonic shear flows. This model called Internal Energy (IE) model takes into account the effects of internal (rotational) energy upon the reaction occurrence and treats it in the same way as the translation energy in reaction collision process. IE model can simulate reaction process precisely by many elementary reactions and is successful in clarifying the details of weak combustion in two dimensional parallel shear flows between supersonic air and sonic hydrogen. The influence of modified plasma (atomic oxygen) flow upon ignition in the supersonic shear flows has been also discussed.