Abstract: Taking the medium deep hole mining in steeply narrow vein of a gold mine in Inner Mongolia as the engineering background， through empirical analogies， numerical simulation and field tests methods， the evolution law of cracks in narrow veins of deep hole blasting under different blasting parameters was analyzed， and the relationship between the blasting parameters and the over-under-excavation percentage of blasting， the density of blasting cracks and the vibration velocity of the surrounding rock particles is obtained. The results show that: when the hole spacing is 1.2~1.4m， the over-under-excavation blasting area tends to be zero. When the burdern is 0.8~1.0m， the blasting fragmentation is more uniform. A burden of 1.0m and a hole spacing of 1.2m can be taken as optimal parameters during deep hole blasting. The field blasting test also verifies the research results of this paper.

Key words: steeply narrow vein; medium deep hole; burden; hole spacing; numerical simulation