Modeling the dynamics of line impact with the friction in Rocking Block has attracted the attention of scientists for a long time. Firstly, this paper converts the line impact to multi-point impact using discretization principle. Secondly, the multi-point dynamic model is then constructed based on the LZB method. Simulation results show that the LZB method and discretization principle are effective in modeling line impact, and the precision are improved with the increasing number of discrete points.