The goal of this clinical trial is to learn about the efficacy and safety of fecal microbiota transplantation in reducing recurrence of colorectal adenomas after endoscopic resection. The main questions it aims to answer are: * the efficacy and safety of fecal microbiota transplantation in reducing the recurrence rate of colorectal adenomas after endoscopic resection. * changes in the intestinal and mucosal microbiota of patients before and after endoscopic treatment. * changes in the intestinal and mucosal microbiota of patients before and after fecal microbiota transplantation. Participants are required to complete one colonoscopy and infuse 150ml of fecal suspension into the terminal ileum under endoscopy, performing the first fecal microbiota transplantation (FMT) on day 0. Subsequently, for 2 days continuously (day 1-2), the participants will undergo microbiota transplantation in the form of oral capsules, taking 40 FMT capsules within one day (20 capsules bid). Subsequently, participants will receive a maintenance treatment with oral FMT capsules (20 capsules bid) at 3, 6, and 9 months (approximately every 75 to 90 days). Participants will undergo their first follow-up colonoscopy between 6 to 12 months(the high-risk adenoma group will receive colonoscopy at 6 months, and the low-risk adenoma group will receive colonoscopy at 12 months).