The invention discloses a cordless telephone based on DECT (Digital European Cordless Telecommunications). The control method comprises the following steps of: converting a current signal output by a sub-telephone RF (Radio Frequency) transmit-receive unit into a voltage signal by a conversion unit in real time; converting the voltage signal into a corresponding numerical value by a sub-telephonecontrol unit; and comparing the corresponding numerical value with a predetermined threshold value in the sub-telephone control unit, wherein the sub-telephone control unit outputs a signal to control the transmission frequency of the sub-telephone RF transmit-receive unit when the corresponding numerical value of the voltage signal is larger than the predetermined threshold value; and the sub-telephone control unit stops controlling the transmission frequency of the sub-telephone RF transmit-receive unit when the corresponding numerical value of the voltage signal is smaller than or equal tothe predetermined threshold value. The transmission frequency of the sub-telephone RF transmit-receive unit can be controlled according to the strong and weak degrees of a communication signal, thereby maintaining stable communication connection between a DECT sub-telephone and a host telephone, reducing the electromagnetic radiation of a communication terminal, saving energy resources and prolonging speaking time of the DECT sub-telephone on the communication terminal.