This study investigates the aquatic insects by Surber samplers at eight sampling sites in Peinan stream' Taiwan from Feb. 1998 to May 1998. As a result of this study' 58 taxa of aquatic insects were found, including 7 orders and 32 families. Of the total number of insects collected, 40% are Ephemeroptera, which is the most abundant insect in the study area. On the other hand' a total of 16 taxa of Trichoptera were collected which were far more abundant than other orders in species number. According to Hilsenhoff's Biotic Index (BI) and Family-Level Biotic Index (FBI), the water quality is excellent or very good in all sampling sites.