From the perspective of tourism urban agglomeration, an evaluation index system of regional tourism competitiveness which involves tourism overall quantity, quality, efficiency, growth power and tourism developing strength is established. By mean square deviation method, this paper analyzes the regional tourism competitiveness, index characteristics and evolvemen trend of three eastern regions in China, based on 6 years (2002-2007) data of 15 selected tourism cities from Bohai Rim, Yangtze River Delta and Pearl River Delta. The result shows that the developing strength of Bohai Rim is the stongest in the three tourism urban agglomeration, followed by Yangtze River Delta and Pearl River Delta. Furthermore, the tourism overall quantity and quality in Bohai Rim are the stongest, but the efficiency is the weakest. The overall quantity and quality in Yangtze River Delta is becoming closer to Bohai Rim, and the efficiency is the storngest, which shows a huge growth potential. The overall quantity and quality in Pearl River Delta are weaker, but it has a more stable growth and its efficiency is stronger, compared to the other two regions.