In recent years, the incidence of colorectal cancer has been continuously increasing, and laparoscopic radical surgery for colorectal cancer is being increasingly applied in clinical practice. In laparoscopic radical surgery for left-sided colon and rectal cancer, the inferior mesenteric artery (IMA) is one of the most important anatomical landmarks, and its handling is also an important step in the surgical process, which can affect the surgical quality, postoperative recovery, and patient prognosis. Inappropriate handling of the IMA during surgery can cause vascular injury, bleeding that can contaminate the surgical field, prolong the operative time, and improper ligation of blood vessels can lead to colon ischemia at the surgical site, thereby increasing the risk of complications such as anastomotic leakage. Therefore, accurate understanding of vascular anatomy is the basis of successful tumor radical surgery in left-sided colon and rectal tumor surgery. The anatomy of the IMA varies greatly, and different results are obtained through various methods such as anatomy, angiography, or surgical research, and there are differences in anatomy due to different races and even regions. It is necessary to summarize and classify them. Although the origin of the IMA varies slightly, there are significant differences in types of branches, number of branches, and the presence or absence of certain branches among different individuals. The results of different researchers are also not exactly the same. Although there is no unified classification system for the anatomical classification of the IMA, the similarities include three major types of branches, including the left colo-sigmoid trunk, the recto-sigmoid trunk or common trifurcation. From the perspective of surgical treatment of colorectal cancer, it is of great significance to analyze the anatomical structure data of the IMA and its branches recorded during preoperative imaging examination and surgery. Therefore, this article summarizes the reported anatomical types and relative relationships between different branches in the literature, describes the normal and variant anatomical structure of the IMA, including a brief overview of relevant embryology, and introduces a new classification system to evaluate and summarize the anatomical structure of the IMA, so as to provide theoretical reference and guidance for surgeons to evaluate the mesenteric vascular system before and during surgery, improve overall surgical quality, achieve sufficient and reasonable tumor radical resection, and optimize surgical treatment.