There is a main chain and continuity, but there is no main chain and auxiliary chain. The futures main contract is the continuous price of the main contract, that is to say, the main contract is the mechanical connection of all the main contracts to form a continuous contract. When the daily trading volume and positions are the largest, a relatively continuous K-line chart will be formed, that is, the main contract. Futures continuity is the K-line connection of the contract with the largest trading volume, that is to say, which contract has the largest trading volume, and the K-line on futures continuity is the K-line diagram of this contract.