〔Abstract〕 Objective To investigate the association between single nucleotide polymorphism(SNP) of PROS1 gene and recurrent spontaneous abortion(RSA) in Baotou Han population. Methods 158 RSA patients and 158 control subjects were selected as the study subjects, and the activities of protein S, protein C and antithrombin-Ⅲ were measured. The rs13062355, rs6441600 and rs12634349 loci of PROS1 gene were genotyped by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP). Non-conditional Logistic regression was used to analyze the correlation between three SNPs of PROS1 gene and the risk of RSA. Results The protein S and antithrombin-Ⅲ activities of RSA patients decreased significantly(P<0.05). PROS1 SNP rs13062355 was associated with the risk of RSA under the dominant model: compared with genotype TT, patients with CT+CC genotypes had a reduced risk of RSA(OR=0.398, 95%CI: 0.249-0.638); SNP rs6441600 and rs12634349 were not associated with the risk of RSA(P>0.05). In the haplotypes constructed by PROS1 rs13062355, rs6441600 and rs12634349, Haplotype C-C-C was statistically different between the two groups(P<0.05). The third-order interaction model rs13062355-rs6441600-rs12634349 was associated with the risk of RSA. Conclusion PROS1 SNP rs13062355 may be associated with the risk of RSA in Han women in Baotou area. Haplotype C-C-C of PROS1 rs13062355, rs6441600 and rs12634349 reduces the risk of RSA. The third-order model rs13062355-rs6441600-rs12634349 interaction has a synergistic effect on the occurrence of RSA.