A microstructure photograph was obtained when laser beam was turned off suddenly during laser cladding to synthesize TiC,,/Al composite. Based on the developed 3-D transient temperature field and fluid flow field simulation program for laser remelting, cladding reaetion features were considered and trial-and-error method was employed to choose every in-situ reaction temperature. According to the temperatures, the reaction enthalpies were added into temperature field calculation. Comparing the simulated temperature with the position lines of the different microstructure zones of the laser sudden stop test, the in-situ reaction temperatures under laser condition could be assessed. Some different parameters of processing were selected for the tests and numerical calculation. Through the agreement between the interface microstructure of the substrate and the cladding layer with the simulated temperature lines, the reliability of the assessed temperatures were proved validly. The assessed temperatures under laser condition could provide a reference for choosing the reasonable processing parameters and the optimized scheme.