The invention discloses a double channels-based relay method. The method comprises the steps that a primary emitter sends a first primary signal; the primary emitter sends out a second primary signal;a secondary emitter sends out a first compound signal with numbers superposed; a secondary receiver detects the first compound signal and cancels the first primary signal; the secondary receiver detects the first compound signal and cancels a first superposed code signal; a primary receiver detects the second primary signal and the first compound signal; the primary emitter sends out a third primary signal; the secondary emitter sends out a second compound signal with numbers superposed and detects the third primary signal, wherein the second compound signal comprises the third primary signaland a second superposed code signal; the secondary receiver detects the second compound signal and cancels the second primary signal and the second superposed code signal; and the secondary receiverdetects the second compound signal and cancels the second primary signal. According to the method, consecutive interference decoding and cancellation are performed in each timeslot, impact of the primary signals and other secondary signals are reduced, and interference of the secondary signals is reduced.