The invention belongs to the field of drainage tubes, and particularly relates to a polyethylene-polyvinyl chloride blend-modified tube and a preparation method thereof. The polyethylene-polyvinyl chloride blend-modified tube aims to solve the technical problems of poor shock strength, high sensitivity to temperature, poor ring stiffness, higher cost and short service life in the existing tube. In order to solve the technical problems, the invention provides a polyethylene-polyvinyl chloride blend-modified tube which comprises the following components in parts by weight: 50-150 parts of polyethylene resin, 50-150 parts of polyvinyl chloride resin, 10-30 parts of nano material, 0.5-5 parts of pigment, 2-20 parts of leadless stabilizer, 1-20 parts of processing assistant, 1-5 parts of lubricant, 0.5-5 parts of antioxidant, 0.5-2 parts of photostabilizer, 1-25 parts of solubilizer, 1-15 parts of impact-resistant modifier, 1-15 parts of enhancer and 0.5-10 parts of coupling agent. The polyethylene-polyvinyl chloride blend-modified tube has the advantages of higher ring stiffness, favorable toughness, aging resistance and greatly higher shock strength.