Objective To study the regulation of BV antibody level of captive-bred cynomologus monkeys.Method BV antibodies of 409 captive-bred cynomolgus monkeys selected randomly were monitored strictly with BV ELISA.Results Nearly all the newborn monkeys had BV antibody,the BV antibody level changes with age increase.At fifth-month old,the BV antibody positive rate reaches the lowest(13.1%) level.Conclusions the regulation of BV antibody level of captive-bred cynomolgus monkeys can be characteristic as having high level after born and decreasing with its age increase as well as increasing after fifth-months old,it is the optimal time for weaning at fifth-month old so as to obtain more BV antibody negative monkeys.