Abstract: With the development of computer and communication technology, electronic money influences greatly the finance as the media of electronic information. In this article, traditional money definition, money multiplier and its influential elements, and three kinds of electronic money are introduced. Then the influence of three kinds of electronic money on money definition and money multiplier is discussed. With the introduction of electronic money, it will change the theory base of traditional money definition and money multiplier. On the basis of traditional theory, the influence of money definition and money multiplier are mathematically analyzed due to the first two kinds of electronic money. Pure electronic money without the basis of traditional theory is analyzed in expectation.