The paper investigated the antihyperglycemic and antihyperlipidemic efficacy and antioxidant capacity of Chimonanthus nitens Oliv. leaf extract (COE) in combination of high-glucose-fat diet-fed and streptozotocin-induced diabetic model mice. Various physiological indexes in diabetic model mice were well improved especially by oral administration of high dose of COE; the results were listed as follows. Fast blood glucose (FBG) level and serum triglyceride (TC), total cholesterol (TG), low-density lipoprotein cholesterol (LDLC), and malondialdehyde (MDA) as well as MDA in liver were significantly reduced; fasting serum insulin (FINS) and insulin sensitivity index (ISI) were both increased; high-density lipoprotein cholesterol (HDLC) in serum was significantly increased; total antioxidant capacity (T-AOC), activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in serum and liver were apparently enhanced; liver coefficient (LC), liver transaminase, and alkaline phosphatase (ALP) were decreased. Furthermore, pancreas islets and liver in diabetic model mice showed some extend of improvement in morphology and function after 4 weeks of COE treatment. In consequence, COE was advantageous to regulate glycolipid metabolism and elevate antioxidant capacity in diabetic model mice. Thus, the present study will provide a scientific evidence for the use of COE in the management of diabetes and its related complications.