A purpose discusses the relationship with U.S. dollars for the stock market and return. Using daily data are U.S. dollars exchange and Taiwan stock return from 2000 to 2004. A research discusses between exchange volatility and Taiwan stock return volatility with exponential GARCH model. Evidence shows stock return is negative by exchange variation and exchange variation is negative by stock return, too. Exchange is influenced more than stock return. So capital afflux and efflux can affect exchange and the stock market. No matter stock return change and exchange variation can be influenced opposite. Because the market only exist a capital, if the stock market has advantage, investors do not invest an exchange market.