Because of the simplification for scenario choices and few reflections of space-time characters, product designers or police makers can’t reference effectively the results of LCA. This paper proposed a new LCA method for design scheme based on multi-scenarios coexistence. First, various life-cycle scenarios of product are summarized and the common attributes are extracted to generate the scenario model. Second, the choice matrix of multi-scenarios is founded based on product statistic. And the probabilities of scenarios calculated from the choice matrix are used to gather together the environmental impacts of multi-scenarios in proportion. Third, the inventory data are collected as per scenario including pollution emissions and character information. The later are used to generate personnel, spatial and temporal factors which reflect the diversity of environmental impacts in different scenarios. Finally, the related issues are discussed including matters needing attention in practical application and what need to research in future.