Considering that soft and fine stools may be related to diet, rectal polyps, rectal tumors and other reasons, you can improve the stool routine, blood routine, colonoscopy and tumor markers and other tests. 1. Dietary factors: the usual diet is mainly fine grains and liquid food, which can easily make the stool soft, and generally has little effect on health. You can check the stool routine to understand the situation of stool. 2. Rectal polyps: If the polyp is large, it will lead to the narrowing of the rectum, and when the stool passes through here and then is discharged, it will lead to the appearance of soft and thin stools. Routine stool and colonoscopy can be done. 3. Rectal tumor: rectal tumor compresses the rectum to make the intestinal tract become narrow, resulting in soft and thin stools. The location and size of the tumor can be clarified by anoscopy or colonoscopy, and the depth of infiltration can be clarified by nuclear magnetic examination. If the softness and thinness of stool still cannot be improved after changing the diet, it is recommended to go to the hospital as soon as possible and take corresponding measures under the guidance of the doctor.