¡yEnterprise Resource Planning¡z(ERP) is an integrated information system consists of different business functions including Financial/Cost, Sales/Distribution, Material Management, Production Planning, etc. It facilitates the business flexibility to adjust for environmental changes such as industries, customer needs, and the status of competitor. The purposes are to reduce the cost, enhance work efficiency, and generate sufficient information for the business decisions. Two enterprises are studied for their ERP implementation in this thesis; they are the InfoChamp Systems Corporation (ICSC) and the Yageo Company (YC). ICSC which started in 2000 A.D. is a spinout company of the China Steel Company after it successfully constructed the ERP system. The strategy of the China Steel Company was to gradually extend the application function from the original management information system. On the other hand, the Yageo Company adopts the SAP package and discards the whole traditional information system. In order to discover how these two enterprises implement the ERP systems, the author interviewed their representatives several times. Besides, the company documents, publish papers and data from their web sites were collected and analyzed. The main conclusions are summarized as the following. 1. The enterprise needs to carefully consider the organization structure associated with possible constraints before the implementation of ERP system. Whether to extend the traditional management information system or to adopt a certain industrial package, the information integration among new systems and old systems is a very complicated issue. 2. The goal of the implementation project should be clarified and specified to all members in the enterprise. In addition, the project manager should be fully authorized to take charge of the whole implementation process. 3. As the enterprise expend their business functions, the information system also needs extra modules. It is not an enduring decision to simply adopt an available package. However, using interface development to integrate the informational system will result in high maintenance cost. 4. The two enterprises emphasis the importance by establishing the project control mechanism. The executive managers serve as the project leader in order to proclaim the ambition of the project success. 5. The contract negotiation with the consulting company requires careful communication. The cost, durations, customization, and the commitment of a successful project should be included. 6. The consistency of the business and information process may enhance business performance. 7. The bureaucratic organization and workflow need a reformation.