This separating circuit is composed of two pre-amplifiers, two isolated amplifiers, front output amplifier, rear out put amplifier, odd harmonic circuit for echo, even harmonic circuit for echo, synchronous time sequence circuit and DC power supply. Because of using odd and even harmonic circuits for echo and synchronous time sequence circuit and based on the principl of voice reflection, the separation of odd from even harmonics in delayed sound (echo) and the ordering of them are performed, so obtaining real echo effect.