The invention discloses a montmorillonite nano-purification technology and a complete set of device for different medical units in a hospital inpatient department, specifically surrounding a montmorillonite nano-pretreatment technology and the subsequent montmorillonite nano-purification integrated technology and device for medical sewage in multiple conventional wards, operating rooms, dressingchange rooms, nurse stations, hemodialysis centers, peritoneal dialysis centers, infectious wards or inpatient buildings, X-ray rooms, radiation intervention and cardiac catheterization angiography rooms and other medical units of the hospital inpatient department, so as to remove suspended solids, heavy metals, harmful ions, harmful organic substances, multiple pathogenic bacteria, parasites, residual antibiotics and other drugs, residual oil stains, surfactants, radioactive substances and the like in the medical sewage of the hospital inpatient department to the greatest extent, so as to reach the national medical sewage discharge standard, ensure the discharge safety of multiple medical sewage of the hospital inpatient department, and ensure the ecological and environmental safety around the hospital. The technology and the device have the advantages of good purification effect, low cost and long service life, and is expected to be applied to multiple medical sewage treatment in inpatient departments of multiple hospitals.