An important task after asset allocation is completed according to risk preference is to check the portfolio regularly so that it does not deviate from the original goal. Rebalancing is to ensure the characteristics of the portfolio through reverse operation, so as to be as close as possible to the original asset allocation goal. Fluctuations in different markets will increase or decrease the value of various assets, and the proportion of investment portfolio will also change. Rebalancing method is mainly used for long-term investment, and funds are extremely suitable varieties. It also follows the process of compulsory investment, selling high and buying low, in which the risk of portfolio is also released.