The disclosure relates to preventing an oxidizer from overheating using cold side bypass during high input for a VOCs treatment system having a series rotor, which may be used in an organic waste air treatment system. The system includes a thermal oxidizer (TO), a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first cold-side transporting pipeline, a fourth cold-side transporting pipeline, a first adsorption rotor, a second adsorption rotor, and a chimney. A cold-side proportional damper is installed between the first desorption-treated air pipeline and the first cold-side transporting pipeline, between the first desorption-treated air pipeline and the fourth cold-side transporting pipeline, or between the first cold-side transporting pipeline and the fourth cold-side transporting pipeline, or the damper is installed on the first desorption-treated air pipeline.