Perioperative prophylaxis, which is not effective when given too early, should be given within 0.5-1 hour before mucosal skin incision at the surgical site, or at the start of anesthesia. It is sufficient to ensure that the antimicrobial drugs in the body, when the surgical site is exposed, can reach the concentration of drugs that will kill bacteria during surgery. Special drugs, such as vancomycin, need to be administered 1-2 hours into the procedure, and additional intraoperative drugs may be considered when the half-life of the drug is more than twice as long. In patients undergoing rectal surgery, oral antibacterial drugs can be given 1 day before the procedure, and the principle of drug administration is as single as possible.