The general clinical manifestations of left-sided colon cancer patients are intestinal irritation symptoms and change of bowel habit, blood in stool, intestinal obstruction, abdominal mass, systemic toxic symptoms, etc. Colon refers to ascending colon, transverse colon, descending colon and sigmoid colon respectively, and the connecting part of descending colon and sigmoid colon is the high incidence area of cancer, so left colon cancer generally refers to descending colon cancer and sigmoid colon cancer, and left and right colons are different in embryology, anatomy, physiopathology, and the clinical manifestations of both of them are also different after the occurrence of tumor. Left colon cancer is mainly characterized by obstruction, with blood, frequent stool and abdominal pain. When there is unexplained abdominal discomfort, go to the hospital for timely examination and early treatment to avoid the deterioration and development of the condition.