In this study, the fauna and biodiversity of thrips of wheat and barley fields was investigated in different environmental conditions, moderate cold climate (Eyvan city) and moderate tropical climate (Darreh Shahr city) in Ilam province, Iran. sampling was carried outweeklyand barley fields. Totally, eightthrips species belonging to six genera and four families were identified. Amongst them, Haplothrips tritici (Kurdjumov, 1912) was the dominant species the abundance of 46.47% and 84.68% in wheat fields, and Thrips tabaciLindeman, 1889was the dominant species the abundance of52.22% and 10.3% in barley fields in Eyvan and Darreh-Shahr cities, respectively. The results showed that Shannon-Wiener, Simpson and Margalef's indices of thrips species in field crops of Eyvan city (moderate cold climate) were significantly higher than those of Darreh-Shahr city (moderate tropical climate), but Evenness was not different significantly between wheat and barley fields in Eyvan and Darreh-Shahr. In general, biodiversity of thrips species in moderate cold climate (Eyvan city) was higher than that of moderate tropical climate (Darreh-Shahr city).