The invention discloses a voice signal transmission method, terminal and system. The method comprises the steps that a first terminal carries out the first amplitude conversion of a voice signal, and obtains an encryption signal, wherein the amplitude conversion enables the amplitude of the encryption signal to be reduced to 1/n of the amplitude of the voice signal, and n is a positive integer; the first terminal enables the encryption signal to be mixed with a noise signal, and forms a frequency mixing signal, wherein the amplitude of the noise signal is greater than the amplitude of the encryption signal; the first terminal enables the frequency mixing signal to be loaded to a preset carrier frequency, so as to obtain a modulated signal and to transmit the modulated signal to a second terminal in a channel. Through the above mode, the method can prevent the voice signal from being intercepted under the condition that the normal communication is not affected.