The aim of this study is to address the issues of low computational efficiency, poor convergence, and difficulty in simulating coupled damage evolution processes of finite element models for honeycomb sandwich structures. Based on the sandwich equivalent theory, a progressive damage failure model for Nomex composite honeycomb structures was established adopting the Continuum Damage Mechanics (CDM) approach. Applying the stiffness degradation method to simulate the process of damage evolution, a subroutine UMAT was introduced into the ABAQUS finite element software to numerically simulate the strength and failure modes of honeycomb core layer. The numerical results using the equivalent model were compared with experimental results and the results computed by refined honeycomb finite element model. It shows that the results obtained from the equivalent model are consistent with the experimental results. The analysis error of the equivalent model is 0.2% higher than that of the refined model. Moreover, the computational efficiency of the progressive damage failure model is ten times higher than that of the refined model.