The invention relates to an ultrasonic signal filter technology and aims to filter out noise signals as many as possible and reserve effective signals in frequency domain data, achieve the purposes ofreducing noise and increasing the signal-to-noise ratio and improve the positioning accuracy of a damaged structure by means of ultrasonic waves. According to the technical scheme of an ultrasonic Butterworth band stop filter method, the expression formula of a Butterworth function is shown in the description, wherein n denotes order of the function, f denotes frequency and fc denotes cut-off frequency. According to the amplitude-frequency curves under different orders and the spectrum distribution characteristics of ideal signals of the function, the function is subjected to conversion as follows: f is equal to the difference of 2*pi and f, the Butterworth function before conversion and the Butterworth function after conversion are taken as transfer function, low-pass and high-pass filters are made respectively and then connected in parallel, and a Butterworth band stop filter is made for filtration. The ultrasonic Butterworth band stop filter method is mainly applied to the ultrasonic signal filtration occasions.