This phase I clinical study was designed to evaluate the safety and immunogenicity of the novel recombinant HPV type 6/11 bivalent vaccine, manufactured by Xiamen Innovax Biotech CO., LTD., in healthy volunteers aged over 18-55 years of age at enrollment. The study volunteers will receive the 3 different formulations of the novel HPV vaccine or placebo administered intramuscularly according to a 0-1-6 month schedule.

Inclusion criteria:

1. Health people aged between 18 and 55 years.
2. Judged as healthy and eligible for vaccination by the investigators through a self-reported medical history and some physical examinations.
3. Written informed consent was obtained from the participants.
4. Able to comply with the requests of the study.
5. Axillary temperature not higher than 37.0°C
6. Men, or non-pregnant women verified by a urine pregnancy test.

Exclusion criteria:

1. Pregnant or breastfeeding or plan to be pregnant within 7 months.
2. Use of any investigational product or non-registered product (drug or vaccine) within 30 days preceding the first dose of the study vaccine or plan to use during the study period.
3. Received immunosuppressed, immunoregulation therapy, or corticosteroid systemic therapy for more than 14 days in the 6 months before entry, except local treatment.
4. Administration of any immunoglobulin or blood products within 3 months preceding the first dose of the study vaccine or plan to use within 7 months.
5. Administration of any attenuated live vaccines within 21 days preceding the first dose of the study vaccine or any subunit or inactivated vaccines within 14 days before vaccination.
6. Had a fever (axillary temperature over 38°C) within 3 days or acute illness requiring systemic antibiotics or antiviral treatment within 5 days before vaccination.
7. Having the plan to participate another clinical trial during the study period.
8. Received another HPV vaccine.
9. Immunodeficiency (such as HIV carriers), primary disease of important organs, malignant tumor, .or any immune disease (such as systemic lupus erythematosus, arthritis pauperum, splenectomy or functional asplenia or other disease which might affect immune response).
10. History of allergic disease or history of serious adverse events occurring after vaccination, i.e., allergy, urticaria, dyspnea, angioneurotic edema or abdominal pain.
11. Asthma that required emergent treatment, hospitalization, oral or intravenous corticosteroid for unstable condition within the past 2 years.
12. Having serious disease of internal medicine, such as hypertension, cardiac disease, diabetes, hyperthyroidism et al.
13. Diagnosed coagulant function abnormality (i.e., clotting factors absent, clotting hemorrhagic disease, abnormal platelet function) or blood coagulation disorder.
14. Epilepsy, except fever epilepsy at under 2 years of age, alcohol-induced epilepsy in 3 years before abstinence, or idiopathic epilepsy requiring no treatment in the past 3 years.
15. Past or current two-stage affective psychosis, not well controlled in the past 2 years or requiring drugs, or h a tendency to commit suicide.
16. Other medical, psychological, social or occupational factors that, according to the investigators' judgment, might affect the individual's ability to obey the protocol or sign the informed consent.