(1) From the perspective of investment volatility, as a passive investment tool, the indexed investment income of index funds strictly follows market fluctuations. This highly volatile investment product can reduce the risk through regular fixed investment, and the effect of fixed investment is the best. However, other investment tools with low volatility, such as bond funds and money market funds, can not give full play to the advantages of fixed-term investment, and their long-term investment income is not attractive. (2) The quality of index funds is more trustworthy. Because the index fund follows the index and belongs to passive investment, the manager of the fund has little personal influence and a lasting style, and investors can rest assured to hold it for a long time. (3) The fixed investment of the fund focuses on long-term investment, and the index fund has a good long-term performance. History has proved that the long-term upward trend of the stock market will not change, and index funds can best replicate the market. Empirical studies at home and abroad show that in the long run, index funds are stronger than 70% active funds and are long-distance runners invested by funds. (4) The cost of index funds is low. Because index funds adopt the investment strategy of M&A, the transaction cost of buying and selling securities is much lower than that of active investment funds, and the management cost is also lower than that of stock funds. Buffett once said: "Low-cost index funds are the most profitable tools for investors in the past 35 years." He suggested that ordinary investors buy cheap index funds in stages over a period of time.