A couple SPH-FEA modelling technique is investigated to determine the suitability of the mentioned technique to model offshore cutting operation of Abrasive Water-jet (AWJ) cutting. For model validation, results are compared to analysis available in literature on abrasive water-jet machining. An AWJ cutting a ductile metal sample with certain thickness and property is modeled and simulated to investigate the impact response and parameters that influence, including impact speeds. To overcome the difficulties of fluid—solid interaction and extra-large deformation problem using finite element method (FEM), the SPH-coupled FEA modeling for abrasive waterjet cutting simulation is presented, in which the abrasive waterjet is modeled by SPH particles and the target material is modeled by Finite Element. Validation is achieved by comparing the model against numerical result available in literature. The coupled SPH-FEA model is compared against previously published results and validated. Then, studies is conducted to determine the erosion rate effect due to change in abrasive types and different flow rates. The depth of penetrations and erosion rate is extracted for analysis. It can be seen that the generated SPH-FEA method is able to simulate the condition of AWJ cutting of offshore steel structure material up to 250 MPa. The fluid-structure interaction in AWJ cutting where the erosion-cutting of steel target material is highly non-linear was modelled by full coupled SPH/FEA. This research demonstrates that the approach can be extended to full-scale AWJ-steel structure cutting simulation through appropriate management of SPH/FEA resources. With a validated model, researchers will be able to manipulate the variables in AWJ to study the efficacy of cutting optimization in offshore decommissioning operations. The novelty in this paper is that the coupled SPH-FEA technique to model Abrasive Water Jetting is used to model cutting of offshore structures. This validated coupled SPH-FEA modelling technique will enable engineers to design new cutting tools that can improve efficiency and efficacy of next generation offshore cutting tools.