A light-emitting diode (LED) light string control system using carrier signal control, comprising: a control module configured to convert a DC voltage (Vdc) into a lighting drive signal (Sl) according to a lighting command (Cl), and an LED light string comprising at least one LED module , and coupled to the control module , and the at least one LED module comprising: a detection circuit configured to generate a detected signal (Ss) corresponding to the lighting drive signal (Sl), a logic circuit configured to determine a first level being a first logic signal, a second logic signal, or a latch signal according to a time duration of the detected signal (Ss) at the first level, an oscillator configured to provide a clock signal (Sck) to the logic circuit for calculating the time duration according to the first level and go into a sleep mode according to a sleep signal (Ssp), and at least one LED , wherein the logic circuit is configured to provide the sleep signal (Ssp) according to the detected signal (Ss) at a second level, or the oscillator is configured to receive the detected signal (Ss) at the second level that is used as the sleep signal (Ssp) for the oscillator , wherein the at least one LED module is configured to latch the first logic signal and the second logic signal as a drive command, and control lighting behavior of the at least one LED according to the drive command, and wherein the oscillator does not provide the clock signal (Sck) when in the sleep mode. a control module configured to convert a DC voltage (Vdc) into a lighting drive signal (Sl) according to a lighting command (Cl), and an LED light string comprising at least one LED module , and coupled to the control module , and the at least one LED module comprising: a detection circuit configured to generate a detected signal (Ss) corresponding to the lighting drive signal (Sl), a logic circuit configured to determine a first level being a first logic signal, a second logic signal, or a latch signal according to a time duration of the detected signal (Ss) at the first level, an oscillator configured to provide a clock signal (Sck) to the logic circuit for calculating the time duration according to the first level and go into a sleep mode according to a sleep signal (Ssp), and a detection circuit configured to generate a detected signal (Ss) corresponding to the lighting drive signal (Sl), a logic circuit configured to determine a first level being a first logic signal, a second logic signal, or a latch signal according to a time duration of the detected signal (Ss) at the first level, an oscillator configured to provide a clock signal (Sck) to the logic circuit for calculating the time duration according to the first level and go into a sleep mode according to a sleep signal (Ssp), and at least one LED , wherein the logic circuit is configured to provide the sleep signal (Ssp) according to the detected signal (Ss) at a second level, or the oscillator is configured to receive the detected signal (Ss) at the second level that is used as the sleep signal (Ssp) for the oscillator , wherein the at least one LED module is configured to latch the first logic signal and the second logic signal as a drive command, and control lighting behavior of the at least one LED according to the drive command, and wherein the oscillator does not provide the clock signal (Sck) when in the sleep mode. <EOS>