Based　on　the　sensitive　character　of　light　sensor,　the　paper　applied　the　median　filtering　algorithm　which　was　used　for　two-dimensional　image　process　on　the　filtering　of　one-dimensional　sensor　signal　and　improved　the　algorithm　with　adding　a　determine　step　about　heavy　interference　signal.　The　research　showed　that　the　miss-rate　and　the　false-rate　of　improved　median　filtering　algorithm　are　0　and　the　deviate-rate　decent　to　0.2%　from　5.1%　in　classic　median　filtering　algorithm.　Therefore,　the　improved　median　filtering　algorithm　can　not　only　contain　the　advantages　of　classic　median　filtering　algorithm,　but　also　filter　the　heavy　interference　signal　efficiently.　The　algorithm　was　better　in　eliminating　the　noise　and　keeping　the　real　signal.