Based on the SHS reaction of Ti-B₄C-sucrose system, Ti(C, N)-TiB₂ ceramic preforms were prepared by self-reactive spray forming technology. The characters of combustion and SHS reaction during the spray process were investigated by water-quenching experiments and collision experiments. The results show that during the spray process, the sprayed particles transform into ceramic beads after the process of heating, surface melting and reacting. The reaction begins with the melting of titanium. And the nitridation and oxidation of titanium go with the whole spray process. Each sprayed particle acts as an individual reactive unit, and there is no macro combustion wave and surface moving in the system. Each particle reacts and transforms in the different time by its own flight track. The transforming extent of the sprayed particles depends on their temperature and size. The sprayed particles with optimal size and high temperature can all transform into ceramic beads. The relative density, micro-hardness and fracture toughness of the sprayed preforms are 97.7%,HV_0.2 2029 and 6.0MPa·m^1/2 respectively.