The invention relates to a method and a system for measuring and calculating greenhouse gas emission reductions. The method comprises the steps of respectively calculating the greenhouse gas emissionreductions of a power grid, a power generation-side and power grid linkage part and a power utilization side and power grid linkage part within a future setting period of time; and measuring and calculating the total greenhouse gas emission reductions according to the above-mentioned three greenhouse gas emission reductions. According to the method and the system for measuring and calculating thegreenhouse gas emission reductions, various greenhouse gas emission reductions of a power grid company are analyzed, various greenhouse gas emission reductions are quantitatively measured and calculated, and aid decision support is provided to the power grid company for formulation and implementation of control plans of greenhouse gas and carbon asset management.