Abstract: The paper briefs on the concept of seigniorage and its measuring ways， comparing with those in America， Japan and related countries. By measuring the possible loss if they are official dollarized， the paper comes to this conclusion: to internationalize a country’s currency and substitute for another， there is a premise that the acting country should compensate for the seigniorage loss that the related country will suffer. As to the ratio of RE/LOSS， the higher it is， the better the effect.