The invention provides a telescopic decompression type steam injection packer, comprising a center pipe and an outer pipe, wherein the center pipe is sealed with the outer pipe; an expansion barrel which expands with heat is sleeved outside the outer pipe; a protective lining is arranged between the center pipe and the outer pipe; the center pipe is connected with the outer pipe through the protective lining; and the protective lining is made of a heat resistant material which is in a solid state at normal circumstances and melted at a steam injection temperature. The telescopic decompression type steam injection packer provided by the invention can be applied to a dense oil steam injection well, can meet the technical requirements on general steam injection and separation layer steam injection of dense oil wells, and can realize two technologies of oil-well oil sleeve annulus sealing and pipe column heat compensation simultaneously. According to the telescopic decompression type steam injection packer, the construction working procedures are reduced, the oil well production cost is decreased and the economic benefit is improved.