This study is a phase III clinical trial to evaluate the immunogenicity and safety of the 13-valent pneumococcal conjugate vaccine (multivalent conjugate) in infants aged 2 months (at least 6 weeks) and 3 months. The main objectives of the study include: 1. To evaluate the immunogenicity of the trial vaccine in infants aged 2 months (at least 6 weeks) following the corresponding immunization schedule compared to the control vaccine; 2. To evaluate the immunogenicity of the trial vaccine in infants aged 3 months following the corresponding immunization schedule compared to the 2-month group; 3. To evaluate the safety of the trial vaccine in infants aged 2 months (at least 6 weeks) and 3 months following the corresponding immunization schedule.

Inclusion Criteria:

Primary immunization phase:

1. The subject's legal guardian voluntarily agreed to allow his child to participate in the study and signed an informed consent form.
2. The subject's legal guardian has the ability to understand the study procedures and to participate in all planned follow-up visits.
3. Full-term pregnancy (37 weeks to 42 weeks gestation) and the birth weight was 2500g~4000g.
4. On the day of the first dose of vaccination, it meets the observation age of this clinical trial (2~3 months of age, with a minimum of 6 weeks) and be able to provide legal identification;
5. Not having received a non-live vaccine within 7 days prior to enrollment and not having received a live vaccine within 14 days;
6. The body temperature <37.5°C (axillary body temperature) on the day of enrollment.

Booster immunization phase:

1. Infants and children who have completed the full process of basic immunization in this clinical trial and are 12 to 15 months of age;
2. According to the opinion of the investigator, the subject's legal guardians and their families can comply with the requirements of the clinical trial protocol.

Exclusion Criteria:

Primary immunization phase:

1. The baby is born in abnormal labor (dystocia, instrumental delivery) or has a history of asphyxia and nervous system damage, and is now suffering from pathologic jaundice, perianal abscess and severe eczema;
2. Have been vaccinated against pneumococcus in the past or have a history of invasive diseases caused by pneumococcus in the past (confirmed by either clinical, serological or microbiological methods);
3. Previous history of severe allergy to any vaccine or drug, such as anaphylactic shock, allergic laryngeal edema, allergic purpura and local allergic necrosis reaction (Arthus reaction);
4. Suffering from congenital or acquired immunodeficiency, or receiving immunosuppressant treatment, such as systemic glucocorticoid treatment for more than 2 weeks one month before vaccination, such as prednisone or similar drugs > 5mg/day (use of local and inhaled/atomized steroids is eligible for enrollment);
5. Have received blood or blood-related products or immunoglobulin treatment before joining the group (hepatitis B immunoglobulin is acceptable);
6. Suffering from severe congenital malformation, severe developmental disorders, serious genetic diseases (such as severe thalassemia), severe malnutrition, etc.;
7. Suffering from infectious diseases such as tuberculosis and viral hepatitis, or parents infected with human immunodeficiency virus;
8. Having contraindications to intramuscular injections such as thrombocytopenia, any coagulation disorder or receiving anticoagulant therapy;
9. Those with a history or family history of convulsions, epilepsy, encephalopathy and psychosis;
10. Asplenia, functional asplenia, and asplenia or splenectomy for any reason;
11. Subjects with other safety risks or conditions that, in the opinion of the investigator, may interfere with the assessment of the purpose of the study.

Booster immunization phase:

1. Subject received any other pneumonia vaccine after primary immunization and before booster immunization;
2. Subject has received blood or blood-related products or immunoglobulin treatment within 3 months before booster immunization;
3. The subjects have known or suspected immunological functional defects since they participated in this clinical trial, including receiving immunosuppressant treatment (such as systemic glucocorticoid treatment for more than 2 weeks in one month before vaccination, such as prednisone or similar drugs > 5mg/day) and their parents are HIV-infected;
4. According to the researcher's judgment, the subjects have any other factors that are not suitable for clinical trials.