The present invention relates to the field of communications. Disclosed are a signal transmission method, device and system, capable of reducing complexity of a receiving device and reducing the cost of the receiving device. The method comprises: a transmitting device obtains a first baseband signal and a second baseband signal, adjusts the period of a first carrier and the period of a second carrier to enable the period of the first carrier to be a non-integer multiple of the period of the first baseband signal, and the period of the second carrier to be a non-integer multiple of the period of the second baseband signal; the transmitting device loads the first baseband signal onto the first carrier to generate a first transmission signal and loads the second baseband signal onto the second carrier to generate a second transmission signal; the transmitting device adjusts the phase of the first transmission signal or the phase of the second transmission signal to allow the phase of the first transmission signal to be different from the phase of the second transmission signal; the transmitting device combines the first transmission signal and the second transmission signal into a mixed signal, and transmits the mixed signal. The present invention is used for signal transmission.