Abstract: This paper introduces a technology which is specially used for removing the plug of well bore or near well bore generally existed in low permeability fields, that is, the matching technology of well cleanout and plug removal with low density foam under negative pressure. This paper studies and perfects the relevant well cleanout foam, oil reservoir treating fluids, foam generator, downhole well cleanout device and operation process. The popularized application of the technology has effectively increased the oil output of individual well (averagely 2.6 t more for a well per day), prolonged the pump inspection period, and thus achieved obvious economic benefit.