Abstract: From the perspective of potential output,this paper defines the concept of coal supply gap,and uses HP Filter to estimate Chinese potential coal supply and coal supply gap from 1980-2010.It verifies the correlation between macroeconomic fluctuations and potential coal supply with GARCH model and investigates whether the relationship of "U" exists,thus provide an important tool for government and coal enterprises analysis of coal industry and its market risk management.From this paper,the coal enterprises,facing the relatively loose situation,should grasp the market rule,strengthen the confidence of coal development,follow up the government policy,and promote the integration so as to reduce the operational risks.