Abstract: Objective To disclose the changes in the susceptibility of Neisseria meningitidis to penicillin antibiotics in China, and explore the mechanism for reduction of the penicillin susceptibility of Neisseria meningitidis strains and the relationship between the susceptibility changes and the polymorphisms of penA gene and PBP2 protein. Methods Both MIC broth microdilution and E-test methods were employed to determine the susceptibility of Neisseria meningitidis strains to penicillin. Amplification and sequencing of penA gene were conducted for analysis of the relationship between penicillin susceptibility changes and penA gene and PBP2 protein. Results The broth microdilution and E-test results revealed four strains with intermediate susceptibility to penicillin but no penicillin-resistant strains. No obvious relationship was found between susceptibility changes and the polymorphisms of penA gene and PBP2 protein. The PBP2 protein of the studied strains was highly conserved. Conclusion Genetic monitoring of changes in the penicillin susceptibility of Neisseria meningitidis should be conducted in future for timely detection of highly drug-resistant strains in order to prevent their spread among the public.