A communicating method of a communication device for connecting to a first network and a second network includes: when a rescheduling condition is reached, rescheduling a wake up period of the communication device for the first network at least according to a wake up period of the communication device for the second network; wherein the wake up period of the communication device for the first network is rescheduled by making the communication device a master device in the first network through adjusting a preference parameter of the first network.