The rapid development of e-commerce has resulted in a large amount of express delivery package waste (EDPW). The optimisation of EDPW systems is important to achieve low-carbon development. To quantify the impact and C-footprint reduction potential, a comprehensive life cycle assessment enhanced by parameterisation and global sensitivity analysis was conducted on Chinese EDPW systems managing fractions of cardboard, paper and envelope, foamed plastic, soft plastic and woven bag. Material flow analysis reveals that 65% of the EDPW is recycled and cardboard is the dominant contributor. The environmental impacts from EDPW to most impact categories are marginal, but the loads to global warming potentials and human toxicity are significant, mainly attributed to the energy and material consumption during package production. From C-footprint perspective, managing 1,000kg of EDPW would generate a load of 834.88 kg CO₂-eq from raw material production and a saving of -524.55 kg CO₂-eq from material and energy recovery. Paper and cardboard incineration can achieve carbon reduction with biogenic-CO₂ emissions, while plastic incineration releases significant fossil-CO₂ that counteracts the savings from energy recovery. Global sensitivity analysis identified proportion of incineration, heat and electricity recovery ratios in incinerators and recycling ratio of cardboard as the major contributors to result uncertainty. Optimising these parameters can achieve a carbon reduction of 177.86 kg CO₂-eq per 1,000kg of EDPW. This paper provides a comprehensive view of the environmental impacts of EDPW in waste management system and novel insights into further optimisation and development of the system from a low-carbon perspective.