The invention discloses a pipe scraping and well washing string for a horizontal well, and relates to the technical field of underground cleaning tools in the petroleum industry. A pipe scraping assembly comprises a pipe scraper, a first magnetic attraction piece and a first wellbore filter, wherein the pipe scraper, the first magnetic adsorption piece and the first wellbore filter are connected in sequence, and the first wellbore filter is sleeved with a casing brush. A well washing assembly includes a second wellbore filter and a second magnetic attraction piece which are connected with eachother. When the pipe scraping assembly is arranged in a vertical well and the well washing assembly is arranged in a horizontal well, the pipe scraper is connected with the second wellbore filter, and the second magnetic attraction piece is connected with a roller bit. When the well washing assembly is arranged in the vertical well and the pipe scraping assembly is arranged in the horizontal well, the second magnetic attraction piece is connected with the first wellbore filter. A cleaning vacuum plant is further arranged, one end of the cleaning vacuum plant is connected with the pipe scraper, and the other end of the cleaning vacuum plant is connected with the roller bit. According to the pipe scraping and well washing string for the horizontal well, the other part is cleaned while pipescraping operation of the vertical well or the horizontal well is carried out, impurities are effectively removed, and the efficiency is high.