Based on the SHS Reactive Flame Spray technology, TiC-TiB2 multiphase ceramic coatings were prepared in the Ti-B4C-C reactive system. Water quenching experiments were used to intercept the intermediate states of the flying particles during the spray course. The macroscopical characteristics, composition, structure, and transforming course of the intermediate-stated reactive products in different flying distance were observed, and the flying combustion course and reactive mechanism of the spray agglomerates in the oxyacetylene flame were discussed. It was showed that there were four types of intermediate-stated reactive products according to their macroscopical characteristics, which were the fully molten solid and hollow ceramic beads, the ceramic particles with molten surface whereas the un-molten core and the completely un-molten ceramic particles. The flying combustion mechanism is studied. The SHS reaction began with the melting of Ti powders. The combustion synthesis of the relatively small spray agglomerates in the core of the oxyacetylene flame was controlled by the diffusion and capillary mechanism and took place in the deflagration mode, whereas the combustion synthesis of the relatively big spray agglomerates in the periphery of the oxyacetylene flame was controlled by the ingredient melting and separating out mechanism.