The research proposes the cognitive semantic analysis of 50 children's blogs. Using cognitive semantic analysis and the experiment method, the research identifies lexical-semantic domains based on the blogs’ concepts. Therefore, it explores the role of culture in children's blogs published by authors from different countries. The cognitive semantic analysis reveals that the key themes in children's blogs are sport, books, entertainment and games, music, fashion, nature and environmental protection, travel and so forth. The sample consists of 625 schoolchildren studied in grades 1, 5, 9 and 11. The research finds there is a cultural component in children's blogs. Future research should focus on the analysis of different blogs, not only for children, but also for adults, and the development of lexical and semantic domains based on key themes and concepts.