This study was aimed to discuss spectators' behavior when watching tennis competition in 2009 21st Summer Deaflympics Games in Taipei. Statistic methods including description, factory analysis, t-test and MANOVA were exercised. The results revealed that the demographic data of most participants was male, married, at age of 31-40, working in commerce and service industry, college graduates, made monthly income between $30, 001 to $45, 000 and resided in the North of Taiwan. As to "spectating information", "discussion on the game", "focus on players' skills" and "atmosphere of the event", male respondents were superior to female respondents; single respondents were better than the married in "spectating information", "discussion on the game" and "focus on players' skills"; people at age of 21-30 were superior to people at age of 31-40 as to "spectating information", "spectating motives" and "focus on players' skills"; with regards to "discussion on the game", participants whose profession in commerce were greater than those in military, education and public organizations; participants with college degree were better than those with graduate school degree in "spectating information" and "atmosphere of the event"; participants whose monthly income below $30,000 were superior to participants whose monthly income above $30,001 in "spectating information", "spectating motives", "discussion on the game" and "atmosphere of the event". Participants resided in the Northern, Southern and Eastern were superior to those in the Middle in "spectating information", "discussion on the game" and "focus on players' skills". It is suggested that the administration of the host shall release precise schedule and relevant information of each game to the public as soon as possible. Making exposure opportunities and spectating motives for the tennis competitions, creating topics for people to talk about, bustling with cheerful excitement will be favorable in attracting more people to spectate the large-scale international tennis competition on the scene.