The efficiency of an oscillating water column (OWC) wave energy converter is analyzed by adopting smoothed particle hydrodynamics and using various geometries for the seabed platform. A two-dimensional, single-phase smoothed particle hydrodynamics (SPH) model is developed to simulate the hydrodynamic characteristics and fluid structure interaction for a fixed OWC located in a numerical wave flume. A linear expression between air velocity in the duct and air pressure in the chamber was imposed for considering the effect of pneumatic model. The measured free surface elevation at the chamber centre and the oscillatory air pressure generated by the fluctuating free surface within the chamber are recorded. The simulation results are validated by comparing against previously published experimental and numerical data. Good agreement is observed in both cases. The geometric dimensions of the bottom platform are modified by altering the platform height and step length. The research demonstrates that by optimizing the step geometry and position for a given wave condition a higher operational efficiency can be achieved.