In this study, Ti3SiC2 was successfully synthesized by the combustion of green samples with a composition formula: (3-x)Ti/Si/(2-x)C/xTiC, where x ranged from 1.0 to 1.8. First, the Ti3SiC2 yield monotonically increased with x, but the maximal yield was less than 50%. The most important factor to increase the Ti3SiC2 yield was found to be the post-combustion heating. The yield dramatically increased to about 90% when a 150-second post-combustion heating time was provided. Furthermore, the yield was proportional to the post-heating time, and linearly increased with the amount of applied post-combustion heating energy. Next, excess Si in the starting reactant powders can further increase the extent of Ti3SiC2. When the mole of Si increased from 1.0 to 1.1, the resulted yield was more than 99%. For the study of reaction mechanism, analyses of sequential layers of quenched samples resulted in the following proposed mechanism. First, TiC, TiSi2, Ti5Si3 were formed from the reactions of Ti, Si and C powders. Next, the eutectic liquids (Ti-Ti5Si3 and Si-TiSi2) covered the TiC particles at the elevated temperature. In the final stage, product Ti3SiC2 was resulted from heating the eutectics and TiC. It is noted that the last two steps required large energy, indicating the post-combustion heating was crucial to produce high-purity Ti3SiC2 product.