Abstract: Effect of composition and raw mateials paricle size on tombustion temperature and propagating rate in the Self-propagating High-temperature Synthesis of TiB₂-xAl composite system was theoretically and experimentally analyzed.With the variation of Al content,the change of tested combustion temperature tends to be the same as that of calculated ones.Combustion propagating rate shows the maximum value when Al content is alout 12 vol% because the liquid metal provides better conditions for mass diffusion and transfer but consumes relatively little energy. Because Al phase does not take part in the direct reaction as that of Ti and B partitles in this synthesis,variations of the particle size of Ti and B have much stronger influence on the SHS process than that of A1.