Bashang Plateau is situated in the northwestern of Hebei Province (41°09′-42°20′, 113°70′-116°30′, 1400-1600m). It is an arid region with abundant solar energy resources, large day and night temperature difference, 387.6 mm average annual precipitation, and 90-100 days frostless period, which leads to the period of crop cultivation is only limited from June to September. Bashang Plateau has complex geomorphic feature, and diversity of plateau vegetations is abundant, such as kinds of vegetables, alfalfa, naked oats, sugarbeet, potato, natural pasture, and shelterbelt etc. Bashang Plateau, where major planting vegetable are cruciferous, has been the fifth vegetable production base of China, and been the semiarid cold farming-grazing transitional zone. In order to identify different species, moths in Agro-Zhangbei station were monitored with ultraviolet light-trap from June to September in 2006 and from May to September in 2007. To collect the trapping insects, the Light-trap was turned on from half past seven in the afternoon until six in the next morning. The moths were frozen 3 to 4 hours or fumigated in poisonous bucket, and than were made to be specimens, classified, identified, and counted. The study of dynamic characteristics of moths community structure will provide basic data of insects for resource utilization and environmental quality monitoring in Bashang Plateau. Data of insects collected during the survey were listed in Excel and constructed on the species abundance, the indices of diversity (H′), evenness (J′), specific richness (S), and individual number (N). The status of Bashang Plateau has been analyzed by using the curve of the moth community species abundance, the indices of diversity, the connection of the evenness and the indices of diversity, etc. The results show that a total of 247 moth species belonging to 173 genera in 16 families were collected from northwestern Bashang Plateau. Noctuidae, including 69 genera and 122 species, was the biggest family. Other three families, Geometridae including 26 genera and 31 species, Pyralididae including 22 genera and 27 species, and Tortricidae including 18 genera and 19 species also have abundant species diversity. The small families were Cossidae, Oecophoridae, Gelechiidae, Yponomeutidae, and Pterophovidae. The dominant species were Scotogramma trifolii（Rottemberg）, Loxostege sticticalis Linnaeus, and Plutella xylostella Linnaeus. The diversity index, specific richness and individual number increased from May to September. The significant correlation was found between indices of diversity and evenness (r=0.9477)，and indices of diversity and number of species (r=0.7785), indices of diversity and number of individuals (r=0.9704 ) were significantly correlated. The index of community similarity of the moths was obvious in different months, and the biggest difference (r=0.7241) appeared between July and Auguest. The curve of the moth species abundance was in accordance with the log-normal hypothesis, and an equation was obtained as S(R)=48exp-〔02 (R-2)〕2. Species of moths in Bashang Plateau was rich, and the community was stable, which indicates that the environmental conditions which moths depend on in Bashang Plateau are stable, and the ecological environmental quality preserves quite well.