The selection of process planning methods during production influences the enterprise′s production process planning performance with determination of the process flow as the most important influencing factor. A new production process determining method that focuses on sustainable manufacturing was developed based on case-based reasoning, expert systems, and feature technology for designing the process flow of a new component. This study matches a new component with preview case process information, modifies the case process information if necessary, and selects the process flow for the new component based on a sustainable development assessment according to the similarities between the case and the sustainable development characteristics. The feasibility and practicability of the method is verified by a case study of a machining process flow design for a new component.