Money flow is a mature technical index in the world. The calculation method is simple. For example, in the minute of 9:50, if the index of a certain sector is higher than that of the previous minute, then the turnover in the minute of 9:50 is regarded as capital inflow, otherwise it is regarded as capital outflow, and if the index has not changed compared with the previous minute, it is not counted. Calculated once every minute and summarized once a day, the difference between capital inflow and outflow is the net capital inflow of the day.