<p>Using microporous raw materials to prepare reticulated ceramic filters for molten steel purification is a novel strategy to enhance the purification efficiency. Steel immersion tests were conducted on two batches of periclase-spinel ceramic filters prepared from microporous magnesia raw material and α-Al₂O₃ micro-powder, and their performance was compared with pure MgO filter. The results showed that the periclase-spinel filters exhibited superior performance. This was attributed to two factors: first, the spinel microparticles within the filter skeletons had a greater advantage over magnesia microparticles in adsorbing spinel inclusions with similar chemical composition from the steel; second, the in-situ generated spinel increased the surface roughness of the skeletons and raised the contact angle between the filter and molten steel, thereby improving purification efficiency. When the α-Al₂O₃ micro-powder content was 15 wt.%, the filter demonstrated excellent purification efficiency, the Al₂O₃ and MgAl₂O₄ inclusions in the molten steel were effectively removed, with an overall inclusion removal efficiency of 83.1%, and the total oxygen content in the steel decreased from 37.5 × 10⁻⁶ to 5.7 × 10⁻⁶, with&#xa0;a reduction of 84.8%.</p>