Colorectal cancer is a common malignant tumor, including colon cancer and rectal cancer. In the early stage of colorectal cancer, there are no symptoms or symptoms are not obvious, only discomfort, indigestion and occult blood in stool. With the development of cancer, symptoms will gradually appear, including change of stool habit, abdominal pain, blood in stool, abdominal mass, intestinal obstruction, etc., with or without systemic symptoms such as anemia, fever and emaciation. Tumor may cause changes in affected organs due to metastasis and infiltration. Colorectal cancer shows different clinical symptoms and signs depending on the location of its development. The main clinical symptoms of colorectal cancer are: 1. The main clinical symptoms of right hemicolectomy are loss of appetite, nausea, vomiting, anemia, fatigue and abdominal pain. Right hemi-colon cancer leads to iron deficiency anemia, showing fatigue, weakness, shortness of breath and other symptoms. Because of the wide intestinal cavity, abdominal symptoms will appear only when the tumor grows to a certain volume, which is one of the main reasons for the late stage when the tumor is diagnosed. Left hemicolectomy is narrower than right hemicolectomy, so left hemicolectomy is more likely to cause complete or partial intestinal obstruction. Intestinal obstruction leads to change of stool habit, constipation, blood in stool, diarrhea, abdominal pain, abdominal cramps and bloating. Stools with fresh bleeding indicate that the tumor is located at the end of the left hemicolectum or rectum. The diagnosis of disease stage is often earlier than that of right hemicolectomy. 3.Tumor infiltration and metastasis The most common form of infiltration of colorectal cancer is local invasion, in which the tumor invades the surrounding tissues or organs, resulting in corresponding clinical symptoms. Anal incontinence, persistent pain in lower abdomen and lumbosacral area are caused by rectal cancer invading sacral plexus. Tumor cell implantation and metastasis to the abdominopelvic cavity form corresponding symptoms and signs. Rectal finger examination can find masses in the cysto-rectal fossa or utero-rectal fossa, and tumor implantation and metastasis widely in the abdominopelvic cavity form abdominal fluid. There are two main ways of distant metastasis of colorectal cancer: lymphatic metastasis and hematogenous metastasis. Tumor cells metastasize to lymph nodes through lymphatic vessels, and also to liver, lung, bone and other parts through bloodstream metastasis. The clinical manifestations of rectal cancer are: 1) change of bowel habit, pus and blood stool, urgency, constipation and diarrhea, etc. In the late stage, there are bowel obstruction, emaciation and even cachexia. In the later stage, rectal cancer often appears blood in stool, which is more in volume, dark red in color, accompanied by mucus, or even mucus blood discharge. About 80% of rectal cancer patients can be found to have hard and uneven masses through natural rectal examination, and in advanced stage, the masses with narrow intestinal cavity can be palpated. 3.Proctoscopic examination can reveal the size and shape of the tumor and can directly take the intervening tissues for pathological examination. Colon cancer is divided into left hemicolectomy and right hemicolectomy, which are clinically different and more complicated. Knowing the specific part of tumor, relevant examination can be performed to understand the specific location of tumor in detail, further determine the nature of tumor, and prepare for the next step to carry out later treatment. Different types of intestinal diseases have different treatment plans, so we should pay attention to the distinction between the two, find out the cause of the disease, and then carry out detailed treatment, so as to improve the survival of patients and prolong their life.