[Objectives]  C-type lectins are common in plants and animals and are involved in immune defense responses, development and signal transductions. Lepidopteran C-type lectins can be divided into three types (S, IML and X) based on their lengths and conserved domains. Little is known about the functions of S-type CTLs. We cloned the Bombyx mori L. C-type lectin S11, quantified its expression, and conducted a preliminary analysis of its function. [Methods]  Based on bioinformatic analysis of all C-type lectin sequences in the silkworm genome, we cloned the full-length cDNA of CTL-S11 with PCR. The nucleic acid and amino acid sequences were compared and analyzed in silico. The recombinant protein was expressed and purified from E. coli. RT-PCR and real-time PCR was used to analyze the tissue profile and inductions. Bacterial agglutination using a recombinant protein was also examined. [Results]  The full-length cDNA of CTL-S11 is 519 bp and encodes 173 amino acids. The corresponding recombinant protein with the HisTag is about 18 ku. RT-PCR indicated that CTL-S11 is expressed in the midgut, fat body, hemocytes and epidermis. Realtime PCR showed that, after feeding, or injecting larvae with bacteria, CTL-S11 was significantly induced at certain time points. The agglutination experiment showed that the recombinant protein induced bacterial agglutination in the presence of Ca²⁺. [Conclusion]  The expression of CTL-S11 was significantly induced by bacteria and a recombinant CTL-S11 protein could induce bacterial agglutination. Therefore, CTL-S11 may function as an immune receptor involved in pathogen recognition in the silkworm.