Concentration and differentiation analysis of tourism economy is a study of attention degree and status quo of specific area development on tourism. It is one of the important measures to obtain a right developing direction and co-operation partners. The development of tourism has special similarities and differences in island system because of the island's relatively independent district feature. This paper collects the data of tourism development in the 12 island counties during 2006-2010, using location entropy and Theil index, and calculates the degree of tourism centralization in Chinese island counties and variation characteristics between provinces and cities, within provinces and cities and overall discrepancy in a time scale. The results are shown as follows. (1) Overall tourism development is disequilibrium in Chinese island counties. Besides, the degree of centralization on tourism situation is low and professional advantages of the island region are not obvious, but at the same time, the space for development is larger. (2) The island's total tourism income differences in Fujian Province have a downward trend, while Zhejiang Province shows an upward trend. This shows that island tourism in Fujian develops towards a balanced direction. Theil index of the general income in island has changed. In 2006 the index in Fujian is bigger than that of Zhejiang, while in 2010 the index in Zhejiang is bigger than that of Fujian, which shows that their general income differences on island's tourism are gradually weakening. (3) The differences between the island counties and their provinces are both increasing, while there is not a great gap between the differences within the group and differences between the groups, but the fluctuations are frequent. Both of the differences between the island counties of their provinces and within the island counties are major contributors to the development differences in Chinese island counties.