I. Overview In recent years, with the continuous improvement of people’s living standard, changes in dietary habits and diet structure as well as the aging of the population, the incidence and mortality rate of colorectal cancer in China have maintained an increasing trend. Among them, the incidence rate of colon cancer has increased especially significantly. Second, clinical manifestations. Early colorectal cancer may have no obvious symptoms, and the following symptoms may appear only when the disease has developed to a certain extent: 1. 2. Change in stool characteristics (thinning, bloody stool, mucus stool, etc.). 3. Abdominal pain or discomfort. 4. Abdominal masses. 5, intestinal obstruction. 6, anemia and systemic symptoms: such as wasting, weakness, low fever. Physical examination. 1.General condition evaluation, general superficial lymph node condition. 2.Abdominal visual examination and palpation, check the presence of intestinal pattern, intestinal peristaltic wave, abdominal masses. 3.rectal finger examination: all suspected colorectal cancer patients must routinely undergo anorectal finger examination. To understand the size, texture, circumference of the intestinal wall, basal mobility, distance from the anal verge, infiltration of the tumor to the outside of the intestine, and the relationship with the surrounding organs. During finger examination, we must touch carefully to avoid missing diagnosis; touch gently, avoid squeezing, and observe whether the finger stains with blood. Laboratory examination. 1.Blood routine: to understand whether there is anemia. 2.Urinary routine: Observe whether there is hematuria, combine with urinary imaging to understand whether the tumor invades the urinary system. 3.Fecal routine: the presence of red blood cells and pus cells should be noted. 4.Fecal occult blood test: it has important value for the diagnosis of small amount of gastrointestinal bleeding.