This paper presents a finite element numerical model of GFRP post anchored concrete slabs (GFRP-PACS) using ANSYS/LS-DYNA software and the Arbitrary Lagrange-Euler (ALE) algorithm’s effectiveness is validated through physics experiment results. A comparative analysis of bond-slip behavior simulations among the share node, CONSTRAIN_BEAM_IN_SOLID and CONTACT_1D methods reveals distinct failure mechanisms under different models while maintaining similarity in the overall simulation process. The study investigates the effects of GFRP reinforcement ratio, concrete slab thickness, and TNT weights on the failure mode, failure volume rate, energy sharing rate, and blast resistance bearing capacity of GFRP-PACS. A damage grading prediction curve for GFRP-PACS is established to assess the impact of material parameters on structural performance. The results indicate that the ALE algorithm can effectively simulate the explosion process of GFRP-PACS. While simulations using different bond-slip models exhibit similar failure processes, they yield distinct final failure modes. Increasing the reinforcement ratio and the thickness of the concrete slab can effectively reduce the axial force in the GFRP bar, and the failure volume rate of the concrete slab, and improve the energy sharing rate and overall blast resistance bearing capacity of the concrete slab. The damage grading prediction curve can assess the impact of changes in TNT weight and slab thickness on the damage.