This　paper　describes　the　performance　and　characteristics　of　AT89C52　micro　controller,　and　the　author　has　designed　a　kind　of　noise　detector,　which　has　the　characte　of　low-cost,　high　precision,　miniature,　using　AT89C52　micro　controller　as　the　core　component.　The　detector　is　used　in　the　workplace,　squares　and　other　public　places　to　detect　the　size　of　the　noise,　providing　the　basis　for　control　of　noise.　©　2011　IEEE.