Abstract: Currency devaluation refers to the decline of purchasing power.Traditionally,it is regarded as the same the phenomenon that money supply exceeds money demand,which is influenced by economic and political factors home and abroad.Or it can be summed up as the mismatching between money demand and money supply.From the view of monetary functions,currency devaluation stems from the fact that the currency issue exceeds the growth rate of social wealth.

Key words: currency devaluation, money demand, money issue