The invention discloses a series feedback balance high-fidelity audio amplifying circuit. All elements are in balanced connection in an up-down hetero-polar symmetry and left-right homo-polar symmetry; in-phase output poles of four input tubes are connected to four corners of a square resistance network respectively; certain ends of two loop feedback resistors are connected with a middle point of a side edge of the square resistance network respectively, namely the middle point of the resistance of the in-phase output poles of the two input tubes in the up-down hetero-polar symmetry, and the other ends are connected with a middle point of an output end on a same side of an amplifying circuit respectively to constitute the series negative feedback balance circuit structure in complete bilateral symmetry.