The reasons for the high interest rate of this investment project are high return and short-term investment.

1. High returns: Zhongyixin investment projects promise high returns to attract investors. High returns usually mean high risks, so investors need to carefully consider the feasibility and reliability of the project.

2. Short-term investment: Some Zhongyixin investment projects may involve short-term investment, such as stocks, futures, etc. These investments usually have higher return potential, but the risk is also higher.