As one of the fundamental tax reforms，flat tax only existed in some tax heavens in the mid 20th century.It was not until the end of 1990s that the economy transiting countries started to adopt the flat tax，and the 13%flat reform in Russia has led to the expansion of the flat tax club.Characteristics of contemporary worldwide flat tax reforms are summarized as following.First，flat tax reforms have showed two periods of explosive growth in terms of time distribution.Second，flat tax reforms have centralized on the Eurasian continent and spread to other areas as well.Third，the tax bases of flat tax countries have standardized and tax rates have decreased.Finally，some countries increased tax rates and returned to progressive income tax.Flat tax is in accord with the“wider tax base and lower rate”tax reform，and is helpful to the income tax reform of China.