Pilot-operated type inverted barrel drain valve

A filtering assembly is arranged in a filtering cavity and comprises a filtering barrel and a flow guide barrel arranged on the periphery of the filtering barrel in a sleeving mode, the filtering barrel comprises a solid flat plate bottom and a filtering wall connected to the flat plate bottom, a plurality of filtering holes are distributed in the filtering wall, and a gap cavity is formed between the filtering barrel and the flow guide barrel; one end of the gap cavity close to the flat plate bottom is closed and one end away from the flat plate bottom is open; according to the pilot-operated type inverted barrel drain valve, the flow guide barrel is arranged on the periphery of the filter barrel in a sleeved mode, fluid in the filter barrel cannot overflow from the specific position of the filter barrel, and therefore impurity blocking or incrustation scale cannot be generated at the specific position easily; and fluid passing through the filtering holes of the filtering barrel is probably collided with the