1. Define the net inflow of main funds: by calculating the net inflow of main funds, you can determine whether the main funds are under control. The following formula can be used: the net inflow of main funds = the purchase amount of large orders-the sale amount of large orders.

2. Set the main control conditions: according to the individual's stock selection strategy and analysis requirements, you can set the main control conditions according to the size, proportion or other indicators of the net inflow of main funds.