Embodiments of the present application provide an I/Q signal transmission method and an apparatus. The method includes: calculating, by a sending end, a first amplitude value and a first phase value of a first I/Q signal; obtaining, by the sending end, an amplitude quantization level of the first amplitude value and a phase quantization level of the first phase value, and the phase quantization level is used to indicate a phase value transmitted per unit of bit width; quantizing, by the sending end, the first amplitude value according to the amplitude quantization level, to obtain a second amplitude value after the quantization, and quantizing the first phase value according to the phase quantization level, to obtain a second phase value after the quantization; and transmitting, by the sending end, the second amplitude value, the second phase value, the amplitude quantization level, and the phase quantization level to a receiving end.