In　this　paper,　on　the　basis　of　shortcomings　of　discontinuity　in　the　hard　threshold　method　and　constant　deviation　in　the　soft　threshold　method,　we　propose　an　improved　threshold　function.　The　numerical　experiments　show　that　the　proposed　method　can　not　only　remove　the　noise　effectively,　but　also　have　greater　flexibility　than　the　two　classical　threshold　functions.　We　can　get　a　higher　SNR　and　better　visual　effects.　©　2013　Springer-Verlag.