Abstract: Making use of them erits of local property in time do-main and frequency domain of thew avelet analysismerhod,combining with digital signal processing techruque,the author designed a band-passfilter based on the w ave let transformation and applied it to the signal-pro-cessing of the rotating-arc.The center fiequncy of the filter could be ad-justed automatically acciordng to the revolving~equency,and the band-width of the filter could be ad justed by changing the software parameters.The experiment results showed that the signal-to-noise ratio of the signalsprocessed by the filter could be improved significantly.