The left side of the navel is mainly the left half of the colon, part of the small intestine, the left side of the kidneys, the left side of the ureter, etc. Women also include the left fallopian tube, the left ovary. 1. The left half of the colon: mainly the descending colon and sigmoid colon, with the absorption of water and help defecation, and the intestinal flora can also synthesize vitamins, providing nutrition for the body. 2. Small intestine: the small intestine is mainly distributed in the center of the abdomen, that is, around the navel, so there will be a part of the small intestine on the left side of the navel, the main function is to digest food and absorb nutrients. 3. Left kidney: there are two kidneys in the human body, located in the navel on the left and right sides, the kidneys are the main organs of the urinary system, with the excretion of metabolites, maintain water-electrolyte balance and other functions. 4. Left ureter: the human body also has two ureters, one on each side of the navel, the main role is to introduce the urine produced by the kidneys into the bladder, and prevent urine reflux. In addition, for women, the organs on the left side of the navel also have ovaries and fallopian tubes, which have the function of producing and transporting eggs respectively. Therefore, when patients experience pain or discomfort on the left side of the navel, lesions of the above organs may be considered and definitive diagnosis and treatment under the guidance of a medical professional is recommended.