The present invention relates to a thermoplastic silicone-polyurethane elastomer and a method for preparing the same. The elastomer is prepared from raw materials comprising : 25-80 parts of a macromolecular polyol, 0-60 parts of a silicone oil or a liquid silicone rubber, 10-50 parts of a diisocyanate, 3-20 parts of a small molecular diol as a chain extender, and 0.1-3 parts of an auxiliary agent. The macromolecular polyol is selected from a silicon-free polyol having a molecular weight of between 1, 000 and 4, 000 g/mol and a polyol modified by silicone through copolymerization or grafting. The small molecular diol is a small molecular diol comprising 10 or less carbon atoms. The thermoplastic silicone-polyurethane elastomer of the present invention has the following excellent performance parameters : a hardness of Shore A40-D80; a tensile strength ≥5 MPa; smooth hand feeling; resistance to dirt such as dust; resistance to liquid permeation; no irritation to skin; good encapsulation effect on PC, ABS, TPU and the like; and a 180° peel strength >25 N/25 mm.