A helium-cooled plate-type divertor design concept has being proposed within the framework of the ARIES power plant study. W tiles are used as sacrificial armor, W-alloy as main structural material and advanced ODS (oxide dispersion-strengthened) steel as the coolant manifold. An impinging jet cooling scheme is employed to enhance the heat transfer characteristics of the concept in the high heat flux zone. This paper describes the design optimization of the helium-cooled plate divertor through parametric studies including thermo-fluid and thermo-mechanical analyses.