進入Web2.0時代後，社群網站產業成長快速，從各大入口網站、部落格網站及社群網站業者所投入的程度來看，社群網站的確是目前極具發展前景的網路新興產業。但觀察目前現有的社群網站研究文獻，大多仍局限於探討社群網站使用者的使用動機、行為等等，對於社群網站的產業環境、廠商策略、行為與績效，以及服務機制的使用、應用創新程度缺乏有力的分析。故本研究藉由SCP產業分析模型來分析社群網站的產業狀況，以『結構—行為—績效』的架構來分析社群網站的產業結構、市場行為與經濟績效之間的關係，佐以產業五力分析理論及產業生命週期理論研究社群產業現況，據以歸納出社群產業的現況及社群網站廠商經營策略的關鍵成功因素，並對未來的社群網站提供建議。 本研究採質化及量化的研究方式。質化部份為分別對台灣主要的四家社群網站（Facebook、無名小站、痞客邦、優勢網）做個別研究，訪談相關資深人員，得出目前產業的現況及各家廠商的關鍵成功因素。量化部份則藉由蒐集問卷樣本資料，分析社群網站使用者的動機與行為、以及他們對於上述四家社群網站功能的偏好。 本研究結果發現，(1) 社群網站的經營模式多為建立一個網路平台，以網站的功能吸引使用者加入並增加黏著度，並以高流量吸引廣告收入，故社群網站一般不會對使用者收費。(2) 社群網站產業沒有傳統上所謂的供應商，與同業間也非傳統的競爭關係。因為使用者可同時使用多個社群網站，社群網站間的使用者也很有可能重複，所以社群網站間並非零和的競爭關係。現今多為互相串連合作，使更多使用者加入與增加停留時間，擴大產業的影響力。(3) 社群網站產業呈現大者通吃的現象，同一類型的社群網站只有前一兩家能夠生存。(4) 社群網站產業的進入門檻低，但新進入者必須有足夠的差異性與創新性才能成功。而現存的社群網站也必須不斷創新服務、提供新功能，才能保有領先地位不被淘汰。(5) 社群網站未來將持續著重於建立使用者之間的人際網路，讓彼此的訊息往來更加簡便迅速。 最後，本研究希望據以歸納出社群產業的環境狀況及各家具代表性的社群網站廠商的關鍵成功因素，並針對未來的社群網站廠商提供建議。 關鍵字：社群網站、SCP產業分析模型、Web2.0、產業五力分析、產業生命週期、關鍵成功因素 / In the Web2.0 era, the growth rate of social networking industry is so fast. The social networking sites are so potential businesses from the investments of major portals, blogs and social networking sites. Almost the thesis are studied the users’ behaviors and motivation’s factors. It’s so lack to study about the industry’s environment, the strategies, conducts, performances of social networking site business. So, this thesis wants to analysis the social networking industry by SCP model. And it wants to analysis the relationship of industry structure, conducts, and performances, and to study the industry status by five competitive force model and industry life cycle theory. It wants to summarize the status of social networking industry, the key successful factors, and the suggestions for future new entrants. This thesis is studied by qualitative research and quantitative research. The qualitative research is that I had a discussion with the senior managers of four famous social networking sites. It discussed the status of the industry and the key successful factors. And the quantitative research is by collecting questionnaire, analysis of community motivation and behavior of website users and their social networking site for the function of the four sites. This study summarized that (1) social networking business model is to build up a networking platform’s functions to attract users to this site, to increased degree of adhesion to earn more high advertising revenue. It can’t charge any fees from users. (2) There is no supplier that like as the tradition business. And the competition is not like as the traditional business due to users can simultaneously access multiple social networking sites. Each user has some different social networking site’s accounts. (3) Just one or two largest sites can survive in similar business model. (4) The entry barrier is so low, but the new entrants must have a sufficient difference and innovation to succeed. (5) the future of social networking sites will continue to focus on interpersonal networks between users, to let social information more easily and quickly. Keywords: social networking sites, SCP industry analysis model, Web2.0, five competitive forces analysis, industry life cycle, the key successful factors