An improved combustion front quenching method was used to investigate the mechanism of self-propagating high-temperature synthesis (SHS) of TiNi from Ti and Ni powders. The microstructural evolution in the quenched sample was observed with scanning electron microscope (SEM) and analyzed with energy dispersive X-ray spectrometry. Also, the combustion temperature of the reaction was measured, and the phase constituent of the synthesized product was inspected by X-ray diffraction. Based on those experimental results, a dissolution-precipitation-diffusion mechanism was proposed and compared with those mechanisms concluded by other authors, thus the mechanism for the SHS of TiNi was systematically discussed. In addition, the influence and necessity of pre-heating before the ignition was discussed.