The invention relates to a design of a reaction regeneration main air system of an oil refining catalyzing device and provides an adjustable energy-saving catalytic auxiliary heating chamber with low main air pressure drop. The adjustable energy-saving catalytic auxiliary heating chamber is mainly provided with a combustor (1), a combustion chamber (8), a heating chamber (10) and a main air inlet pipe (5), wherein the lower part of the main air inlet pipe which is arranged at the upper part of the combustion chamber and vertical to a cylinder body (9) of the combustion chamber is divided into a combustion primary air passageway (3) and a bending secondary air passageway (7) by a partition board, and the heating chamber (10) is communicated with the bending secondary air passageway (7); the primary air passageway (3) is communicated with the combustor (1) by a combustor air door (2) which can adjust primary air and is arranged on the combustor (1); and a damper regulator (6) for adjusting the air input of the combustion primary air passageway and the bending secondary air passageway is arranged on the bending secondary air passageway in the main air inlet pipe. The invention can reach the high pressure drop combustion effect when the main air of the catalyzing device assists the heating chamber to work, and ensure the running with low pressure drop and power consumption during normal running.