Pursuing the green design (GD) of products is highly beneficial in the alleviation of environment burdens. In order to gain such benefits, GD is involved in entire product lifecycle. During the product lifecycle, energy-saving is one of the main roots of environmental pollution, with the optimal calculation of the total energy consumption for GD being an important path to reduce the environmental pollution. The objective factors of decision-making problems in the traditional product design are usually three: life、quality and cost; but from the viewpoint of GD, energy consumption should also be considered. Energy design factor (E) is the essential coefficient of the model of the energy consumption throughout the entire product lifecycle. In this paper, a multi-object decision-making model of energy-saving design for GD is put forward, in which the objects of life (L), quality (Q), cost (C) and energy design factor (E) are considered together. A case study on a decision-making problem of energy-saving design in the design process of a machine tool’s transmission is analyzed, the result showing that the model is practical.