Objective To investigate the B virus infection rates in rhesus macaques changing with seasons. Methods B virus antigen ELISA kit was used to detect B virus antibody of 54 weanling rhesus macaques for 13 consecutive months. Results In December, January, February, March and April, the number of B virus positive monkey is increased significantly, and in other months the number of B virus positive monkey is relatively stable. Conclusion B virus infection is affected by the seasons, in spring B virus infection rates is higher, that can strengthen the precautions or regulate environmental factors in high seasons to reduce B virus infection and improve the monkeys quality.