Abstract: For the problems of flying rocks and uneven blocks usually appeared in the HML open-pit mine and identify the reasonable length of blast hole blockage, we used LS-DYNA to establish models of bench blasting with three different length of blockage (2.5 m,3.5 m, 4.5 m respectively) in the open-pit mine. From the peak particle velocity (PPV) of the simulation result on the three conditions, it shows that the longer of length was, the higher the PPV reached. Through the analysis of the maximum principal stress and the PPV, we concluded that 4.5 m was the suitable length of blockage of this mine, which extended the identification method of length of blast hole blockage.