Large oil tank bottom cleaning device and using method thereof

The invention relates to the technical field of oil tank cleaning, and discloses a large oil tank bottom cleaning device which comprises a positioning assembly, the positioning assembly is configured to be positioned with an oil outlet pipe in the center of the bottom face of an oil tank, and a rotating seat is arranged on the positioning assembly; an oil scraping support is arranged at the bottom of the trolley body and is of a U-shaped structure, the opening end of the oil scraping support elastically abuts against the bottom face of an oil tank in the advancing direction of the trolley body, the lower end of the oil scraping support elastically abuts against the bottom face of the oil tank, and an oil suction pipe is arranged on the inner wall of the lower end of the oil scraping support. An oil pump connected with the oil suction pipe is arranged on the trolley body, and the output end of the oil pump is connected to the outside of the oil tank through a pipeline. A flexible inhaul cable is arranged betwe