本文建構一個兩國兩貨幣的搜尋模型，探討貨幣政策與政府交易策略如何影響兩國貨幣的流通價值。公部門遵循的交易策略是只能接受並持有本國貨幣。當人們接受並持有本國貨幣與外國貨幣，本國貨幣供給微幅增加，將提高公部門與民間交易的機率，本國貨幣需求增加、本國貨幣升值。隨著本國貨幣的通膨率持續攀升，本國貨幣報酬率下降的效果超過公部門與民間交易機率增加的效果，本國貨幣價值下滑。當公部門向海外採購需求很大，即使外國商家辨識本國貨幣的成本極高，他們也會接受本國貨幣，本國貨幣將成為國際通貨。

This paper develops a two-country, two-currency search model to study how monetary policy and government transaction strategies affect the circulation values of the two currencies. Government agents follow exogenous trading policies, only accept and hold domestic currency. When domestic currency inflates slightly, increasing the trading probabilities of government and private agents, domestic currency appreciates due to increased demand for domestic currency as long as private agents accept and hold domestic and foreign currencies. As the domestic inflation rate goes up the decrease in the rate of return of domestic currency becomes the dominant effect, and thus the domestic currency value declines. When government demand for overseas goods is very large, foreign sellers accept domestic currency even if the cost of verifying this domestic currency is high. Therefore, domestic currency becomes an international currency.