Sustainability assessment is growingly recognized as an effective analytical methodology and management tool useful for managing and improving sustainability performance. In this study, a novel approach of sustainability benchmark assessment is presented to overcome the performance quantification and hierarchization deficiencies of current sustainability assessment methods. A conceptual model demonstrating how sustainability assessment of mechanical manufacturing systems in the industrial sector produces mutually beneficial energy, economy and environment outcomes that serve to reduce energy and cost demand and mitigate environmental challenges is illustrated. Through constructing the sustainability index system encompassing energy, economy and environment perspectives, the energy, economy and environment-oriented assessment models are presented. Furthermore, two concepts concerning sustainability benchmark and sustainability benchmark rating are proposed to benefit the sustainable performance quantification and hierarchization of mechanical manufacturing systems. This method based on sustainability benchmark assessment is applied to a small mechanical manufacturing enterprise in China through which users can visualize and identify sustainability performance for different mechanical manufacturing systems. This approach can offer the effective feedback for users to enhance process management and technical improvement (process optimization) and to reconsider the energy, economic, and environment in new production cycle, enabling sustainability continuous cycle improvement. This study contributes a new theoretical insight for sustainability assessment by offering relational ties with technical and managerial aspects in support of industrial sustainability.