Lawyer's letters are becoming more and more common in foreign related legal issues, usually aiming at urging the other party in a formal and strong manner, playing the role of warning, deterring, urging and so on. A professional lawyer's letter can effectively restate the legal fact, dominate in the later litigation, and even solve the conflict and dispute in a short time, avoiding the litigation procedure and thus reducing the litigation cost. However, LOD may not only fail to achieve the client's purpose, but also lead to unnecessary infringement disputes. It can be seen that understanding and grasping the legal nature and legal risks of lawyer's letter is important for conducting civil and commercial activities (e.g. trading) in China.