The reaction pathway of combustion synthesis (CS) of Ti5Si3 in CuTiSi system was explored through a delicate microstructure and phase analysis on the resultant products during differential thermal analysis (DTA). The formation of CuSi eutectic liquids plays a key role in the reaction pathway, which provides easy route for reactant transfer and accelerates the occurrence of complete reaction. Cu initially reacted with Si to form Cu3Si by a solid-state diffusion reaction, which further reacted with Cu to form CuSi liquids at the eutectic point of ~802°C; then Ti was dissolved into the surrounding CuSi liquids and led to the formation of CuTiSi ternary liquids; finally, Ti5Si3 was precipitated out of the saturated liquids by a solution–reaction–precipitation mechanism. The reaction pathway in CS of titanium silicide (Ti5Si3) could be described briefly as: Cu(s) + Ti(s) + Si(s)[RIGHTWARDS ARROW]Cu3Si(s) + Ti(s) + Si(s)[RIGHTWARDS ARROW](CuSi)(l) + Ti(s)[RIGHTWARDS ARROW](CuTiSi)(l)[RIGHTWARDS ARROW]Cu(l) + Ti5Si3(s).