The present invention relates to fully humanized antibodies, specifically to a fully human anti-RANKL antibody, a nucleic acid molecule encoding the antibody, and a composition containing the antibody. The present invention further relates to uses of the antibody in preparation of drugs for prevention and treatment of bone loss related diseases, especially osteoporosis, arthritis osteolysis damage or tumor bone metastasis and other diseases. According to the present invention, the antibody is specifically bound with human RANKL and blocks the activity of the human RANKL while the potential immunesuppression of the human RANKL on human body is reduced, the antibody has good stability, and the defect of the non-uniformity (heterogeneity) of the IgG2 antibody production on the batch quality identification is avoided.
