Study on diversity and distribution of insects was conducted in seven small islands of Karimunjawa Nationanal Park, Central Java from March 24 to April 7,2006, using two collection methods i.e pitfall traps and sweeping nets. The study collected 108 species of insect from the seven small island included 9 ordo of 44 families. They were Lepidoptera (27 species), Odonata (7species), Orthoptera (8species), Mantodea (2species), Blattodea (9species), Hymenoptera (20 species), Diptera (8species), Coleoptera (12species) and Hemiptera (15 species). The highest number of species was collected from Karimunjawa Island (96species), while other island were low: Genting (30species), kumbang (23species), kembar (26species), Nyamuk (56species), parang (50species), and bengkuang (23species). Base on fuction on nature, these insect could be divided into phytophagous, pollinator, decomposer, pasitoid, vector and unknown. Three species of butterflies were rediscovered during this study - they were euploea crameri karimondjawensis, euploea sylvester karimondjawana and idea leuconoee karimondjawana, while one species neptis columelle karimondjawae has not been found yet. Shannon, Simpson's and Alpha indexes, and similarity of jackard to compare the difference among the islands is disccussed.