Objective To observe the biological characteristics of db/db mice, and to provide the basis for application of db/db mice in experimental research. Methods Spontaneous type 2 diabetes BKS.Cg-Dock7^m+/+Lepr^db/JNju mice and wild type mice of the same age were used in this study. Their fasting blood glucose was determined at 8,12,16, 20 and 24 weeks of age, the body weight was recorded at 10, 12,16, 20 and 24 weeks of age, the levels of serum insulin, total cholesterol and triglyceride were measured, the organ weight and liver coefficient were determined, and the liver and pancreas were taken for pathological examination at 24 weeks of age. Results The db/db mice maintained a high level of fasting blood glucose and body weight. Levels of serum insulin, total cholesterol, and triglyceride were significantly higher than the wild type mice. Compared with wild type mice, liver weight and kidney weight were also significantly increased. Obvious pathological changes of liver and pancreas were observed in 24-week old db/db mice. Conclusions db/db mouse has obvious characteristics of type 2 diabetes, such as hyperglycemia, hyperlipidemia, and hyperinsulinemia, can maintain stable levels of high blood glucose,and is an ideal animal model for experimental study of type 2 diabetes mellitus.