[Objectives]  To investigate the expression of the Apis cerana Niemann-Pick disease type C2b (AcNPC2b) gene, an intracellular cholesterol transporter that can recognize and bind to the cell walls of several microorganisms. [Methods]  The AcNPC2b gene was expressed in a prokaryotic bacteria and the purified recombinant protein obtained used to immunize mice to prepare polyclonal antiserum. The transcriptional and translational activity of AcNPC2b in various tissues were then detected by fluorescent quantitative PCR and western blotting, respectively. Finally, the function of AcNPC2b was investigated using a microbial binding assay. [Results]  AcNPC2b contains signal peptide and ML domains with 3 disulfide bonds. A phylogenetic tree shows that AcNPC2b and the DmNPC2b gene of Drosophila melanogaster cluster on the same sub-branch. qRT-PCR indicates that AcNPC2b gene expression is generally weakly down-regulated, then continuously up-regulated, in CSBV-infected larvae. A recombinant protein of about 16 ku was obtained. Western blotting results indicate that the AcNPC2b protein is most highly expressed in the head, thorax and midgut, followed by the antennae, Malpighian tubules and fat body. Immunoblotting indicates that the AcNPC2b protein was slightly up-regulated in CSBV-infected larvae compared to healthy larvae. The microbial binding assay showed that the recombinant protein rAcNPC2b protein binds directly to Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Beauveria bassiana, which suggests that it plays a role in pathogen recognition and the immune response. [Conclusion]  There were differences in both the transcription and translation of AcNPC2b between healthy and CSBV infected larvae. A recombinant AcNPC2b protein was able to recognize and bind to pathogenic bacteria. These results provide a theoretical foundation for subsequent in-depth study of the molecular function of the AcNPC2b protein.