The present invention relates to an encoding method, a decoding method, an encoding circuit and a decoding circuit for single-channel communication. The encoding method for single-channel communication includes: combining a clock signal and a data signal to a long- and short-code signal, wherein the long- and short-code signal includes a long-code signal and a short-code signal, a pulse width of the long-code signal is consistent with that of the clock signal, and a pulse width of the short-code signal is consistent with that of the clock signal; and the long-code signal and the short-code signal have different duty cycles. According to the encoding method, the clock signal and the data signal are encoded at the same time, which can reduce the circuit complexity and thus the wire bonding for chip packaging.