Factor C is an endotoxin-sensitive, intracellular serine protease zymogen which initiates the coagulation cascade system in the horseshoe crab hemolymph. The special lipopolysaccharide (LPS) binding activation of FC makes it a potential drug for anti-LPS treatment and has a high commercial value. Based on the sequence of reported FC from Japan horseshoe crab, two pairs of primers were designed. The total RNA was extracted from amebocytes of Chinese Tachypleus tridentatus and the cDNA was separated into two parts and were cloned using RT-PCR, respectively. FCs from different geographical areas showed high homology in sequence. The whole FC cDNA was cloned into pET-28a (+) containing T7 promoter and recombinant expression plasmid pET-FC was constructed. The recombinant plasmid was transformed into E. coli BL21 (DE3). Recombinant FC was expressed as inclusion body when the expression strain was induced with 1 mmol/L IPTG. Refolded recombinant FC was confirmed to be active by bacteriostatic assay in vitro. The results of Western blot also suggested the recombinant FC may be able to cleave itself partly and produced an extra immunoblot band.