Relevant to the self-propagating high-temperature synthesis (SHS) process, an analytical study has been made to investigate dependence of its flame initiation on system parameters, such as operating and physicochemical parameters, in order to obtain ignition energy. Use has been made of the heterogeneous theory which can satisfactorily account for the premixed mode of the bulk flame propagation supported by the nonpremixed mode of particle consumption. It is found that the ignition energy strongly depends on not only heat loss, but also particle size of the higher melting-point metal. which has nor been captured in the homogeneous theory.