As Web-based e-procurement has become an important business avenue for the improvement of inter-organisational process efficiency, its implementation for purchasing direct materials nevertheless implies establishing collaboration mechanism among supply chain participants based on the adopted Internet based infrastructure. However, the value of Web-based procurement to the supply chain participants remains an arduous task for researchers. This study proposes a Web-based e-procurement impact model based on supply chain orientation, which includes both operational and strategic impacts. Specifically, the strategic dimension is about partner relationship, and the operational efficiency dimension includes supplier performance, buyer performance, process integration, and process automation. To prove the proposed model's contribution, a questionnaire survey was conducted on 137 firms in Taiwan who have all participated in e-procurement related projects. The results verify that the electronic execution of purchasing activities improves both the operational efficiency dimension and the strategic dimension. Furthermore, partnership has a positive impact on supplier performance and buyer performance.