There is a positive correlation between the sensitivity of investment cash flow and the degree of financing constraints faced by enterprises. Its view is based on the following reasons: due to the imperfection of the market, endogenous financing and exogenous financing are irreplaceable, and endogenous financing has a cost advantage; Because enterprise investment is influenced by financing factors, the financing cost of enterprises with different financial characteristics to obtain external financing is different; When the external financing cost is high, the enterprise will retain the surplus for investment, and the internal cash flow fluctuates greatly; When the external financing cost is small, the investment is less dependent on the surplus. When internal cash fluctuates, enterprises can make full use of external financing to seize investment opportunities. Therefore, some scholars believe that the sensitivity of investment cash flow can be used as an indicator to measure financing constraints.