A simple and efficient method for disposing of waste low-density polyethylene (LDPE) express packagingbags is proposed in this paper as a way to minimize waste and address the energy shortage at the sametime. In addition to following the production of carbon nanotubes (CNTs) derived from LDPE, the applicationof CNTs as electrodes for supercapacitors was attempted. Waste LDPE bags were pyrolyzed andcarbonized with catalyst using a dual-temperature reaction system, a designed 450 C pyrolysis temperatureaccompany with different carbonization temperatures (650 C, 700 C, 750 C, 800 C, 850 C), andtreatment durations (0 h, 2 h, 4 h, 6 h) were investigated. As determined by FE-SEM and FE-TEM, the CNTssynthesized at 750 C showed a finer tube diameter, much more uniform distribution, bamboo-like structure,as well as the highest yield of 41.9 %, and carbon conversion of 61.2 %. As being charged and discharged10,000 times, the electrode remained a 93.16 % capacitance and a 92.85 % Coulomb efficiency. A dual-temperature reaction system could be utilized to recycle waste LDPE efficiently, and the LDPEderivedCNTs could be applied for supercapacitors.