Metformin is a first-line drug for patients with type 2 diabetes. But its poor lipid solubility and side effect, such as gastrointestinal discomfort,swirl and nausea,impacts its due effect. Other biological activities of metformin, such as its antibacterial activity is also affected by its structure. Thus, modifying metformin has clinical practical significance. Here we make a review on metformin derivatives synthesis based on metformin.