Inclusion Criteria:  Healthy volunteer between 8 - 18 months old; Proven legal identity; Guardian(s) of the volunteer should be capable of understanding the written consent form, and such form should be signed before the infant being included into this study; Complying with the requirement of the study protocol;  Exclusion Criteria:  Axillaty temperature > 37.0 °C; Any significant abnormity of heart, lung, liver, spleen, lymph nodes, or pharynx; Acute disease or acute stage of chronic disease within 7 days prior to study entry; Prior vaccination with mumps vaccine or with history of mumps infection; History of allergy to any vaccine or vaccine ingredient, or serious adverse reaction(s) to vaccination, such as urticaria, difficulty in breathing, angioneurotic edema, abdominal pain, etc;  Receipt of any of the following products:  Any subunit vaccine or inactivated vaccine within 14 days prior to study entry; Any live attenuated vaccine within 28 days prior to study entry; Any other investigational medicine(s) within 30 days prior to study entry; Blood product (e.g., immunoglobulin) within 3 months prior to study entry; Any immunosuppressant, cytotoxic medicine, or inhaled corticosteroids (except corticosteroid spray for treatment of allergic rhinitis or corticosteroid treatment on surface for acute non-complicated dermatitis) within 6 month prior to study entry; Epilepsy (except febrile seizures), history of seizures or convulsions, or a family history of mental illness; Autoimmune disease or immunodeficiency; Congenital malformation, developmental disorders, or serious chronic diseases (e.g., Down's syndrome, diabetes, sickle cell anemia or neurological disorders); Severe malnutrition; Diagnosed coagulation function abnormal (e.g., coagulation factor deficiency, coagulation disorder, or platelet abnormalities); Any other factor that suggesting the volunteer is unsuitable for this study based on the opinions of investigators;  Participants with the following conditions between day 0 - 28 of this study would be included in the full analysis set (FAS), but would be excluded from the per protocol set (PPS):  Receipt of any other investigational or unregistered product (drug or vaccine); Receipt of immunosuppressant (dosage of corticosteroid ≥ that in 0.5 mg prednisone per kg weight per day) for > 14 days consecutively, except for inhalant or locally administrated corticosteroid; Receipt of immunoglobulin and/or other blood product; Newly diagnosed autoimmune disease or immunodeficiency (e.g., HIV infection);