近年來，網際網路發展迅速，公共關係人員利用網路媒體向利益關係人進行溝通已為必然之勢。孫秀蕙曾以2003年台灣五百大服務業之企業網站做為分析樣本，建立可供衡量的企業網站公關效果指標。奠基於此，本文將以2010年《天下雜誌》1000大企業大調查資料中的500大服務業作為研究樣本，將「企業網站公關效果評估指標」界定為「營利性組織透過網站與目標公眾進行溝通的表現程度」，用內容分析法來了解目前服務業設置網路媒體之現況，進而分析各種經營與發展的可能性；並透過個案訪談，以了解企業經營網路媒體的模式究竟為何，其操作細節又是如何。 本研究以Esrock & Leichty對企業網站內容之架構為基礎，將功能與技術指標合併，並新增互動性指標，共分為目標公眾內容、網站功能與互動性三構面，與組織性因素（產業別、員工人數、營業額、有無上市等）進行交叉研究，以了解組織性因素對於網站公關效果可能的影響。 研究發現，時間因素不影響組織性因素與網站建置之關係，但公共議題討論之發展隨時間影響有所改變。本研究推估營業額較小的企業，因其所擁有媒體資源較少，故更積極大膽運用網路媒體。而大企業在資訊發佈上考量較多，在網路策略上則較為保守。整體言，企業越來越重視網路媒體，各種內容與運用形式隨時間與科技發展更趨完善。 / With advances in technology, the terrain of public relations practices needs to be re-defined as new media bring about substantial changes in communication patterns. Based on the framework Hsiu-hui Sun had established in 2003, which attempts to measure the effectiveness of corporate website, this study used quantitative content analysis to assess current Taiwan's top 500 corporate of service industry's effectiveness of public relations on online media which are defined as the degree of performance level for corporations’ internet communication. In addition, a case study is conducted to understand the rationale and operational details of the online corporate public relations. Adopting the theoretical framework from Esrock & Leichty, this study combines the functional and technical indicators and categorizes them into three dimensions, including target audience contents, interface features, and degree of interaction. Because past research found that the size and resources of organizations were positively related to their overall performance, including the quality of public relations efforts. Therefore, in the present study we posit that target audience contents, interface features, and degree of interaction as indicators of public relations effectiveness are associated with organizational resourcefulness (i.e., factors). Findings suggest that time factor does not affect the relationship between organizational factors and the presence of website. However, time factor is relevant to the awareness of the importance of corporate social responsibility. We conclude that small business with fewer media resources tends to leverage internet media more progressively. On the contrary, big corporations are more conservative toward utilizing the Internet. To sum up, corporations nowadays take the role of the Internet media more seriously. The content and applications of the Internet become more important for business communication as time and technology evolves.