Tin-based oxides and their alloys with high specific capacities are considered as promising anode materials for Na-ion batteries. However, the tin-based oxides and their alloys suffer from a large volume variation and particle agglomeration during the charge-discharge process, resulting in electrode pulverization, capacity fading, and poor rate performance. In this paper, Bi/SnOx particles anchored on an ultrathin carbon layer (Bi/SnOx@C) were synthesized by a sodium chloride template method, and a uniform Bi/SnOx@C heterostructure is constructed. The ultrathin carbon layer can effectively inhibit the agglomeration of Bi/SnOx particles and increase the specific surface area of the electrode material, providing more active sites. Bi/SnOx can also contribute the more specific capacity. The synergistic effect of ultrathin carbon layer and Bi/SnOx composite can effectively improve the cycling stability, which is of great significance for the construction of high-performance electrode materials.