The invention relates to a method for encapsulating a piezoelectric polymer thin-film sensor, which comprises the following steps of: cutting micropore structure crosslinked polypropylene (XPP) membrane into the membrane with a size of 1cm*5cm; depositing metal electrodes on the two surfaces of the XPP membrane through vapor after a charging process; adhering metal wires (1) on the upper and lower surfaces of the XPP membrane through conductive adhesive to form the piezoelectric polymer thin-film sensor (3); placing the piezoelectric polymer thin-film sensor (3) into an encapsulating thin film (2) of which the melting point is less than that of the XPP membrane to vacuumize; adjusting the temperature of a thermocompressor to the melting point of the encapsulating thin film (2); and adhering the vacuumized piezoelectric polymer thin-film sensor (3) with the encapsulating thin film (2) into a whole. The method for encapsulating the piezoelectric polymer thin-film sensor is simple in process and low in cost and is quick to perform; and the piezoelectric polymer thin-film sensor encapsulated by the method can be bent freely, is ultrathin, water-proof, dust-proof, anti-static, high temperature resistant, strong in insulating ability, good in sealability and pressure resistance and long in service life, and can be widely applied in the fields of communication, sensors, memory cards,severe military environment and the like.