Porous TiAl3 intermetallcis are of great interest due to its excellent properties and widely applied in filtering apparatus, separation material and catalyst carrier. In this study, interconnected pore-structures have been synthesized by diffusion or thermal explosion (TE) reaction sintering with different heating rates. The thermal characteristics such as temperature-time curves, exothermic change and visual images indicate that the sample experienced a significant TE reaction at higher heating rates. Results shown that the sample was ignited at 672 °C and then rapidly increased to combustion temperature of 1169, 1110 and 933 °C in tens of seconds with the heating rate of 15, 10 and 5 °C∙min⁻¹ respectively. Meanwhile, TE represented the uniformity of volume combustion, instantaneous reaction and rapid cooling to furnace temperature, the amount of heat released during TE reaction dropped from 1303 to 963 J g⁻¹. This indicates that the entire sintering process was controlled by TE and the pre-diffusion reaction before the melting temperature of Al atom, which would affect the subsequent combustion reaction. Thermodynamic data explained that the reaction mechanism is mainly step-controlled diffusion reaction at a low heating rate (1 °C∙min⁻¹), while the energy gradually accumulated and thermal explosion (TE) reaction become obvious with the increasing of heating rate (from 2 to 15 °C∙min⁻¹).