<p>Heterojunction as negative electrode of sodium ion battery has become a research hotspot. It can not only solve the problem of single-layer negative electrode but also improve the stability by synergy. It has the advantages of high capacity, good magnification, and long cycle. This article is based on first principles and constructs a SiC/Nb₂CO₂ heterojunction composite material using ceramic material 3C-SiC and MXene material Nb₂C. The potential performance of SiC/Nb₂CO₂ heterojunction as a negative electrode material for sodium ion batteries is explored in depth. When constructing heterojunction materials of Nb₂C and 3C-SiC functionalized with O, it was found that the electrochemical performance is excellent, with abundant structural adsorption sites and a significant advantage in theoretical capacity of 588.81 mAh/g. The open circuit voltage at the maximum adsorption concentration is in the ideal range of 0–1&#xa0;V, which can suppress sodium dendrites and improve battery safety and stability. This study reveals the influence of 3C-SiC and Nb₂CO₂ composite materials on Na ion storage performance, providing a new path and theoretical support for optimizing negative electrode materials for sodium ion batteries, as well as ideas for related research fields, and promoting innovation in the development of sodium ion battery materials.</p>