An operating method for a one-time password with an updatable seed. The method comprises: a one-time password entering a dormancy mode after being powered on and initialized; being woken up when an interrupt is detected; entering an interrupt processing flow; setting a wakeup flag; entering a key processing flow when a key wakeup flag is set; judging a system state and a key manner; and completing the functions of programming seed data and generating a password according to a judgment result. According to the present invention, on the premise of guaranteeing the security, a user is permitted to program and update seed data in a one-time password, thereby facilitating the use of the user.