Organisms with pH optima for growth in alkaline range are defined as alkalophilic microorganisms,which are mainly distributed in natural soda lake,alkaline desert and soil．Various kinds of microorganisms,including fungi,actinomycetes,yeasts and viruses were isolated in addition to bacteria．They possess special structures and physiological functions to adapt the limiting facter of alkaline for their life．Therefor,it is important to explain adaptive mechanisms.Alkalophiles are able to produce alkaline enzymes and new products．Many enzymes have been produced in industrial scale and applied in practice. 

The distribution．species,adaptive mechanisms and applied prospects of alkalophiles will be briefly intruduced in this paper．