Reactive liner shaped charge jet (RLSCJ) penetrates thick steel plate by experiments and model analysis combined. The experimental reactive material liners with a density of about 2.3 g/cm3, composed of mass matched ratios of Al/PTFE powders, are consolidated by a cold pressing/sintering process. Four standoffs of 0.5, 1.0, 1.5, and 2.0 CD (charge diameter) are selected to conduct the penetration experiments. The experimental results show that, compared with traditional metal liner shaped charge jet against thick steel plates, a relative larger hole diameter but lower depth accompanying with fragmentation effects of penetrating steel plates are produced by RLSCJ. To understand this penetration behavior of reactive jet, an analytical model is developed to discuss the influence of initiation delay time of reactive jet and standoff on penetration depth. Analysis shows that the penetration depth strongly depends on initiation delay time of reactive jet. With increasing the initiation delay time, the penetration depth increases significantly, showing a good agreement with the experiments. Moreover, to further understand the fragmentation mechanism effect of the thick steel plates, the effective mass of reactive jet inside the penetrating hole and its deflagration-induced structural damage effect are analyzed theoretically. Prediction results fit well with the experiments, including crack generation and propagation in the thick steel plates, and the number of fragments.