Aims The purpose of this study was to investigate the characteristics of gut microbiota of children with obesity in Harbin, China and to screen anti-obesity strainsin vitroandin vivo. Methods and Results The gut microbiota of children with obesity and normal-weight children were investigated by high-throughput sequencing, and based on the different composition in gut microbiota, the strains with potential anti-obesity properties were screenedin vitroandin vivo. Compared with normal-weight children, the Firmicutes to Bacteroidetes ratio in children with obesity decreased. Moreover the relative abundances ofLactobacillus and Bifidobacteriumin children with obesity were decreased, while the relative abundance ofAkkermansiaincreased. After a series of screeningin vitroandin vivo, nine strains were found inhibiting the body weight gain of HFD-fed mice, of which two strains showed significant effects (P < 0 center dot 05). Conclusions There were significant changes in gut microbiota of children with obesity from Harbin, China. The obtained strains showed obvious anti-obesity effects, and the screening methods used in this study were effective. Significance and Impact of the Study This study enriched the research results on the characteristics of gut microbiota of children with obesity in different regions of the world. Moreover we established a new and effective method for screening anti-obesity strains, and obtained effective strains.