Owing to the enforcement and implementation of green environmental directives, e.g., the Restriction of Hazardous Substances (RoHS), Waste Electronic and Electrical Equipment (WEEE), and Eco-Design Requirements for Energy Using Products (EuP) in European Union, the “green” concept is fast becoming the global market trend and the base of industrial development. In order to prevent global environment from serious impact of industrialization and pollution caused by human business activities, developing products fit in with environmental concerns (called green product development or eco-design) becomes a critical task for product designers and producers. Consequently, green product design capabilities become the key competence for enterprises to stay globally competitive. In this research, an integrated green product design methodology and system are developed to support environmental conscious, energy-using products development. The proposed methodology adopts life cycle assessment (LCA), quality function deployment for environment (QFDE), theory of inventive problem solving (TRIZ) and the projections of green conceptual design improvement based on back-propagation neural network (BPN) approach. LCA is developed for assessing and comparing the environmental impacts of (human) activities for the production and provision of goods and services. QFDE extended from QFD is a method of translating high-level objectives (voice of customer and voice of environment) into concrete actions and requirements. It is one of the design techniques that aim to satisfy customers’ needs at the product concept design phase. The forecast of design improvement model based on BPN is developed for the R&D decision support of environmental conscious product design to reduce the time frame of product development. TRIZ is used to support R&D to create innovative product design ideas effectively and efficiently during the concept design stage. Finally, this research will present a green concept design case study of electric adaptor demonstrating the proposed eco-design methodology and system.