Life cycle assessment (LCA) can help enterprises evaluate their product’s environmental impacts through the entire product life cycle (PLC). On the basis of the evaluation result, phases which need to take activities to reduce the environmental impacts can be found out. However, the activities taken in a phase may influence the environmental impacts in other phases, so the effect of the activities should be re-evaluated. Under the pressure from the market, enterprises need to assess the effect of these activities quickly. Nevertheless, re-evaluate by using conventional LCA is a time-consuming work. This paper proposes a novel approach to re-evaluate the environmental impacts of product based on LCA and Pareto rule which can reduce the time of assessment. A printed circuit board (PCB) case study is conducted using this approach. The outcome shows that the new approach can re-evaluate the environmental impacts more efficiently without influence the validity.