Abstract: Based on the traditional pre-splitting blasting technology and taking the super deep hole pre- splitting blasting project of a certain iron ore in Northwest of China as the background， the formula of strengthening charge at the bottom of the ultra deep hole is put forward on the basis of engineering practice， that is， the height of the bottom strengthening charge is 0.1 L≤L1≤0.2 L， and the depth of L[∈]15， 30） in the formula is the hole depth. Based on the parameters design of the super deep hole pre-splitting blasting at the bottom， ANSYS/LS-DYNA numerical simulation software is used to simulate the stress field distribution and the peak pressure. The results show that the pre splitting blasting effect is best when the bottom strengthening charge is at 4 m~4.5 m. It is put forward that strengthening the bottom charge height L1 ranges at 0.15 L≤L1≤0.17 L. The field tests have been carried out， and the test results are all ideal and the bottom slit effect is good. It is proved that the strengthening charge technology at the bottom of the ultra deep pre-splitting hole is feasible and can effectively guide the mine production.

Key words: Super deep hole pre-splitting blasting, Strengthening charge at the bottom, Numerical simulation, Field test