Numerical analysis on the process of the flame kernel initiation in spark ignition for methane/air combustible mixtures has been conducted. Spark energy near the minimum ignition energy is applied in the electrode gap and the early stage of the flame kernel initiation in investigated. The peak of minimum ignition energy for equivalence ratio of methane/air mixtures is located in the region of lean mixtures. When ignition energy is slight bigger than the minimum one, flame kernel initiation requires a certain period of time. In addition, hot gas spurts from the electrode gap at early stage of spark ignition processes and gradually quenches. In hot gas region, a local equivalence ratio is higher than that of the ambient gas at the latter stage of the flame kernel development.
