Obesity is a chronic metabolic disease in which excessive accumulation of body fat leads to overweight. Cassava starch is a digestible starch， and the current research on it mostly focused on structural analysis and in vitro function evaluation. This study was based on a mouse obesity model， using high-throughput sequencing technology to study the total cholesterol (TC)， triglycerides (TG) and immune index immunoglobulin A(IgA)， immunoglobulin G (IgG)， immunoglobulin M (IgM) in the blood of modeled obese mice after ingesting cassava starch. Studies have shown that compared with the control group， the levels of TG， IgA， IgG， and IgM were significantly higher than those in the control group. Cassava starch intake it promoted the increase of the relative abundance of bacteria that could efficiently catabolize carbohydrates such as Bifdobacterium and Dorea， but also promotes the proliferation of pathogenic bacteria such as Clostridium. Ingestion of cassava starch promoted changes in the microbial composition of the gut tract of mice. At the same time， abundant carbohydrates also provided sufficient energy sources for the body， thereby increasing energy storage and making mice more prone to obesity.