摘要： Metal laser direct deposition (MLDD) is a typical process in additive manufacturing (AM), which permits the build of complex and fully dense metallic parts by using laser to melt the metal powder layer by layer. However, the process is characterized by high energy consumption and low energy efficiency. This paper established an empirical model to characterize the relationship between process parameters and energy efficiency for MLDD based on the essence of thermodynamics physical energy conversion. Additionally, a recognition method of cross-sectional profile of the deposited layer was achieved by adding tungsten carbide (WC) powder, which greatly improved the measurement reliability. Taguchi experiment and regression identification method were applied, and the relative error of the model was less than 10%. The results show that laser power has significant influence on the process energy efficiency of MLDD. The energy efficiency of single-track multi-layer stacking (SMS) process and multi-track single-layer lapping (MSL) process increased by 5.7% and 50.3%, respectively, under the optimal process parameter condition. The proposed model can be used effectively for the energy efficiency evaluation and offer the potential for improving the sustainability of MLDD.