Abstract: Gas problem seems quite serious with the extension of mining depth of coal in China, especially the widespread of the upper corner gas exceeds the limit, which is a key restraining factor to production of last, stable, safe and efficient of mine.To discuss the basic reason of upper corner gas accumulation, theoretical analysis was done on gas migration law in goaf according to percolation theory in hydromechanics.Through the numerical simulation was done on established mathematical model of seepage and distribution of gas of goaf, flow distribution of gas of goaf was analyzed It provides theoretical foundation for upper corner gas concentration distribution analysis and the concentration prediction, which has important guiding role for control of upper corner gas.

Key words: Goaf, Gas migration, Upper corner, Percolation theory, Numerical simulation