Abnormal implant placement is a common challenge in clinical work, including root direction, occlusion direction, mesial direction, distal direction, buccal (lip) direction, tongue (palate) direction, a total of 6 directions. Clinicians should pay great attention to the risk of many complications due to improper placement of implants. Understanding the etiology is the premise to effectively prevent the complications of implant restoration, and this article will discuss the causes, the classification of complications and related treatment principles and treatment plans from 6 different directions of abnormal implant positions.