The Green factory mark system validated by the Ministry of Economic Affairs will be officially launched in 2012. The assessment of green plants covers not only in the prohibition of harmful substances during the manufacturing process, reduction of unnecessary waste and promotion of environmental protection policies, but also extends to the whole supply chain from raw materials, parts suppliers to proceed with the environmental protection policies, and ultimately helps to achieve the objective of the green supply chain. However, there are no related laws to require part suppliers to adhere to green production plant objective currently in car industry. This study focuses on how customers affect and influence suppliers¡¦ environmental commitment based on its own environmental strategies and environmental performance requirements. The study is mainly from the constructs of customer¡¦s environmental strategy and customer¡¦s environmental performance requirements which includes moderators of contract, evaluation, and encouragement to investgae the relationship with suppliers environmental commitment. The study takes 246 suppliers of Honda Taiwan Motor Co., Ltd as sampling and utilizes Likert five-level scaling method from 1 to 5, from ¡uStrongly disagree¡v¡B¡uDisagree¡v¡B¡uNeither agree nor disagree¡v¡B¡uAgree¡v¡B¡uStrongly agree¡vto confirm hypothesises of the study. According to the results of this study, the predictive factors for improving suppliers¡¦s environmental commitment are customer environmental performance requirements; customer environmental strategy and contract in order. The statistical results are significant. In other words, suppliers will raise its environmental commitment according to its major customers¡¦ environmental performance requirements and environmental strategies. Suppliers also agree that contract restrictions signed with major customers would enhance and raise its environmental commitment. The study takes Honda Taiwan Motor Co., Ltd. as an example trying to see how to raise suppliers¡¦ environmental commitment without any laws reinforcement and expects to set the standard for other companies in Taiwan.