Modern economy, the interest rate as the price of money, not only restricted by many factors in the economic and social, and changes in interest rates to have a great impact on the economy as a whole, as a result, modern economists are studying the interest rate decision problem, pay special attention to the relationship between the variables and the balance of the economy as a whole, the interest rate decision theory has experienced the classical interest rate theory, Keynes's interest theory, interest rate in loanable funds theory and is-lm analysis as well as the contemporary evolution of dynamic interest rate model, the development process. In general, us interest rates fall and the dollar weakens. Us interest rates rise and dollar trends favour. A change in the price of U.S. Treasury bills, especially long-term Treasury bills, can help to predict the direction of the U.S. dollar. If investors think the us inflation is under the control, then under the existing Treasury bonds interest rate to attract, especially short-term Treasury bills, will attract investors, bond prices to rise. It could become extremely complicated when picking a bank or lender to advance your student loans. Quite a few students choose Key Bank Student Loans to advance their studies while in their sophomore college year and are generally pretty delighted by the degree of service they receive. These particular loans include several options and programs that happen to be developed for various requirements. 2. The factory system period At present, countries around the world is frequent use of interest rate leverage to implement macro-control, interest rate policy has become a central bank to control money supply and demand, and a major means of regulating economic, interest rate policy in the position in the central bank's monetary policy more and more important.