Clinic Trial to Evaluate the Safety and Immunogenicity by Different Sequential Schedules of bOPV and IPV

Inclusion Criteria: * Term pregnancy (37-42 weeks), birth weight meets the standards (over 2500g), aged from 60 days to 90 days old; * parent(s) or guardians are able to understand and sign informed consent for participation; * Participants or guardians are able to attend all planned clinical appointment and obey and follow all study instructions; * subject didn't administrate with any immunoglobulin after birth (except the Hepatitis B specific immunoglobulin) and did not administrate any other live vaccines within 28 days or inactivated vaccines within 14 days; * Axillary temperature ≤37.1℃. Exclusion Criteria: Subjects will not be eligible for the study if any of the following criteria is met： * Subject who has a medical histroy with Hypersensitiveness, eclampsia, epilepsy, cerebropathia and neurological illness * Subject who is allergy to Streptomycin, neomycin and polymyxin B * Subject with immunodeficency or are in the process of immunosuppressor therapy * Clinical diagnosis of poliomyelitis; * Acute febrile disease or infectious disease; * Labor abnormal, asphyxiation rescues, congenital abnormality, developmental disability, serious chronic diseases; * Allergic to any ingredient of vaccine or with allergy history to any vaccine; * Taking orally injecting of steroid hormone over 14 days in the recent month; * Febrile (temperature ≥ 38.0°C) in three days; * Diarrhea with one week (more than 3 motions a day); * Taking part in another clinical trail; * Any OPV vaccinat…