The low thermal conductivity and high chemical stability of corundum-mullite refractories have garnered attention for high-temperature insulation and acid-corrosion-resistant applications. A 3D extrusion-based method (direct ink writing) utilizing clay-alumina-silica fume foaming inks was employed to create corundum-mullite refractories with controllable structures (non-porous surface, porous interior). The rheology and printing ability of the inks were modified by adjusting the additives (dispersant and foaming agent) content. Printing parameters, specifically pressure and nozzle moving speed, were adjusted to enhance the precision of the printed construction. The impact of extrusion pressure in the ink on the surface structure of printed products was also investigated. The properties of the corundum-mullite refractory were evaluated by heating it from 1200 °C to 1500 °C, resulting in improvements in acid corrosion rate (from 1.9 % to 14.7 %), thermal conductivity (from 0.35 to 1.65 W/m·K), and compressive strength (from 20.1 to 45.5 MPa), respectively. The Ashby-Glicksman model (closed pore) was employed to forecast the thermal conductivity of the porous refractory with complex pore structures, proving to be a beneficial choice. After acid corrosion for 12 h, there were minimal microcracks and pores on the surface of the refractory prepared at 1500 °C, and the acid corrosion rates were less than 3.4 %. This study illustrates the effectiveness of optimizing printing parameters to adjust pore structure and enhance refractory properties.