The invention relates to a jet flow combined operation acid extrusion transformation method of an SAGD (Steam Assisted Gravity Drainage) mudstone interlayer. The method comprises the following steps that a sieve pipe of a horizontal section of a steam injection well is perforated through hydraulic jet; an oil sand reservoir and a mudstone interlayer are further perforated; transformation liquid is discharged and extruded into a continuous oil pipe; the pump pressure of the steam injection well is controlled in the liquid extrusion process; the maximum well bottom pressure of the steam injection well is enabled to be 1MPa smaller than the formation fracture pressure; meanwhile, the well bottom pressure of an oil producing well is maintained to be the standing water pressure; the transformation liquid enters the oil sand reservoir through a borehole perforated through hydraulic jet, further contacts the mudstone interlayer, and gradually corrodes sand-mud ingredients in the mudstone interlayer; and the pressurization and volume expansion of the oil sand reservoir are realized through a hydraulic pulse generator after the liquid extrusion is completed. The transformation method provided by the invention is applicable to a sieve pipe well completion thick-oil oil sand reservoir; the mudstone and sand-mudstoneinterlayers between upper and lower wells and above an upper well can be effectively penetrated and corroded; a volume expansion region which surrounds the upper and lower wells and is uniformly distributed along the horizontal well section is formed; and the circulation preheating effect and the finial single well harvesting rate are improved.