The invention discloses an on-line waste gas treatment system of a waste cable high-temperature treatment device. The on-line waste gas treatment system comprises a first dust collection mechanism, an energy transduction mechanism, a first regeneration mechanism, a settling mechanism, a dust collection module, an absorption mechanism, a discharging mechanism, a circulation mechanism, an unloading module and an adsorption filtering mechanism, wherein the energy transduction mechanism is communicated with the first end of the first dust collection mechanism; the first regeneration mechanism is communicated with the second end of the first dust collection mechanism; the settling mechanism is communicated with the energy transduction mechanism; the dust collection module is arranged below the settling mechanism; the absorption mechanism is arranged behind the settling mechanism; the discharging mechanism is arranged above the absorption mechanism; the circulation mechanism is communicated with the absorption mechanism; the unloading module is arranged below the absorption mechanism; the adsorption filtering mechanism is arranged between the absorption mechanism and the discharging mechanism. Aiming at the phenomena that by using a conventional dust collection system, wastes cannot be efficiently utilized and waste gases is discharged into the natural environment, the modules cooperate with one another, not only are waste gases efficiently recycled, but also substances in the waste gases are recycled, and environment pollution is avoided.