Nitrogen-doped Reduced Graphene Oxide (N-rGO) has raised tremendous interest in water treatment owing to its fascinating properties. There are two main ways to synthesis N-rGO, which is hydrothermal method (HM) and annealing method (AM) in water treatment field. But as an efficient catalyst in water treatment, the process of N-rGO production also has some environmental impacts. This study assesses the life cycle environmental impacts of N-rGO produced by HM and AM, and explore the implications of varying the key production parameters with a thorough sensitivity analysis. The results show that the environmental impacts of HM is higher than that of AM, so AM route is more available to scale-up production than HM route. For AM route, electricity reduction is the most efficient way to decrease the environmental impacts, and the next is ethanol recovery. For HM route, ethanol recovery is the most efficient way to decrease the environmental impacts, and the next is electricity reduction.