When the interest rate is expected to rise, the short position of treasury bonds futures can be appropriately increased and the portfolio duration can be reduced; When the expected interest rate goes down, the long position of treasury bonds futures can be appropriately increased to improve the portfolio duration. If the interest rate moves as expected, you can profit from it. Although it is also possible to adjust the duration of the portfolio by buying and selling cash bonds, the transaction cost of using treasury bonds futures is lower and more convenient.