High performance thermoelectric powders or bulks can be quickly obtained by self-propagating high- temperature synthesis (SHS) or its derivative methods. In the process of preparing skutterudite by SHS technology, unsteady SHS reaction is easy to occur, which leads to impurity phase in the powders compact after reaction. In this work, the SHS process of the skutterudite was investigated via regulating the power density of the laser (η) and preheating temperature (T₀) by laser induction and preheating of powders compact, respectively. The change of combustion mode for the skutterudite of CoSb₃ was observed and the process window for single phase was obtained. As a result, with fixed η and increased T₀, the state of the SHS process changes correspondingly, i.e., reaction stop→unsteady spiral combustion→steady-state combustion→unsteady spiral combustion. With η=3.75 J·mm^-2 and 250 ℃≤T₀<370 ℃, the single-phase of CoSb₃ can be obtained successfully.