Owing to the diversity of green evaluation index and multiple-factor related to the process evaluation, existing green evaluation of manufacturing process lacks a set of effective knowledge management model. It leads to the high cost and inefficiency of analysis and evaluation process. A green evaluation model for manufacturing process based on multi agent is presented. Based on the model, green evaluation support system of manufacturing process based on multi agent is developed with the knowledge base introduced. The implementation strategy of green evaluation for manufacturing process is implemented by the closed-loop knowledge chain, which is composed of knowledge mining, knowledge transferring, knowledge application and knowledge feedback. The feasibility of this system is verified by an instance of the valve stem manufacturing process in a valve factory.