Matrix-assisted laser desorption ionization mass spectrometry (MALD1/MS) is a new technique developed in recent years.It can be broadly applied to many aspects of modern life science.Basic principles of this technique are discribed,some important research results in our group are also discribed, for example,accurate protein molecular weight determination and the separation and identification of protein mixtures.The feasibilities and problems of MALD1/MS applied to fast protein sequencing and DNA sequencing are also discussed.