Abstract: Structural internal explosion damage is one of the main ways to destroy the target, the damage pattern and damage range is the main way to characterize the damage power of structural internal explosion, and its analysis method can strongly support the prediction of weapon damage effect and structural protection design. In this paper, a finite element analysis simulation method was used to study the damage power of structural internal explosion with multi-box structure. Based on the simulation results, the variation of damage range and damage pattern with equivalent and structural parameters was analyzed, and the dimensionless numbers and calculation method was proposed to analyze the damage range, number of damage walls and damage distribution pattern of multi-box structure, and the damage distribution pattern and damage range table were drawn. The proposed analysis method was verified based on the available experimental. The results show that the method can be able to predict the damage pattern and damage range with the discontinuous variation of explosion equivalent.