The performances of four liquid-jet cooling systems for light emitting diodes (direct, indirect, hybrid double-side, and hybrid jet-fin cooling) were evaluated using three-dimensional Reynolds-averaged Navier-Stokes analysis. The steady incompressible turbulent flow and conjugate heat transfer in the cooling systems were calculated using the shear stress transport turbulence model. The numerical results for the maximum temperatures at the chips were validated by comparison with experimental data. The maximum temperatures at the chips and the pressure drops through the systems were selected as the performance parameters, and were evaluated at four different flow rates. Connection methods for the inlet ports were also tested to enhance the uniform cooling of the chips. The hybrid double-side cooling method showed the best cooling performance. The best inlet connection method depended upon the mass flow rate.