The invention relates to a DNA walker for SARS-CoV-2 detection and a preparation method of the DNA walker. The DNA walker for SARS-CoV-2 detection comprises a walking chain W, a locking chain L1, a locking chain L2, an orbital chain Tr, a target chain T1, a target chain T2 and gold nanoparticles. The invention also provides a preparation method of the DNA walker, and a method for detecting SARS-CoV-2 by using the DNA walker. According to the DNA walker provided by the invention, visual SARS-CoV-2 detection is realized, the DNA walker has the advantages of few interference factors, low price and good stability, and meanwhile, the sensitivity can reach 1nM. When the DNA walker or the kit provided by the invention is used for detection, a reverse transcription step is not needed, the use of enzymes, labels or modifications is avoided, the result is visualized, the requirement on complex equipment is reduced, and a convenient, economical, rapid and reliable method is provided for SARS-CoV-2 virus detection.