The seller's price transaction is also called "outer disk" and the buyer's price transaction is called "inner disk"; If the "outer disk" is significantly larger than the "inner disk", it means that the buying is strong and the stock price is expected to rise. If the "inner disk" is obviously larger than the "outer disk", it means that the seller is stronger and the stock price may fall. The comparison of internal and external disk data has reference significance for large-cap stocks, while small-cap stocks are easy to be controlled by bookmakers, which has less reference function.