The variety fluctuation of each link in the industrial chain of coal coke steel is linked, which is determined by its variety attribute. Iron ore and coke are smelted into pig iron in proportion, and then made into rebar from crude steel. If we look at futures volatility, we can't just look at the industrial chain characteristics of the varieties themselves. After all, futures prices are generated by bidding. Although it must conform to a certain spot operation cycle, the price fluctuation depends more on the trading behavior of market participants, the attention of funds, the activity of variety trading and so on.