The invention discloses a low frequency electromagnetic ultrasonic guided-wave receiving signal amplifying method and device. The device comprises a protection circuit, a multistage amplifying circuit and multiple clamping circuits; the protection circuit is used for limiting an amplitude value of an initial high voltage signal in an initial target signal and outputting a first target signal; the multistage amplifying circuit is used for amplifying the detected first target signal, wherein the multistage amplifying circuit comprises at least three stages of amplifying circuits, all stages of amplifying circuits in the multistage amplifying circuit are connected in series in sequence, and the amplified first target signal is used for detecting the damage degree of a detected material; each clamping circuit in the multiple clamping circuits is used for limiting the amplitude of the high voltage signal output by the parallel amplifying circuit, wherein each stage of amplifying circuit in the multistage amplifying circuit is connected with one clamping circuit in parallel. The method and device solve the technical problem that a low frequency electromagnetic ultrasonic guided-wave receiving signal cannot be accurately detected in prior art.