Abstract: Nanfen open-pit coal mine in order to speed up the hanging wall expansion speed，the 12m step mining changed to 18m. In this paper，the problems of site elevation in blasting，more roots and blocks produced in blasting，and more dumping of part of rock into stope are analyzed，and the control mea⁃ sures are put forward. The results show that the above problems are mainly caused by the decrease of deto⁃ nation velocity of deep emulsion explosive，the increase of resistance line，the change of lithology and the unreasonable detonation sequence when the 12 and 18 m steps are integrated. By optimizing blasting design and site management，the blasting quality is effectively improved and the mine production cost is reduced.

Key words: 18 m step, blasting quality, control measures