The purpose of this study is to assess the role of turbulence on the lubrication performances of coupled journal-thrust water-lubricated bearing with micro grooves using a numerical model. The results of the simulation model are compared to the published experimental data to verify the validity of the numerical model. The load capacity, maximum film pressure, and local Reynolds number variations with the rotating speed, eccentricity, radial clearance, axial geometric gap, and micro groove depth for coupled journal-thrust water-lubricated bearing are examined. Furthermore, the calculated results under the turbulent flow are compared with those under laminar flow for coupled and separate bearings. The results show that the turbulence effect can improve the lubrication performances by enlarging fluid pressure and load capacity of the coupled journal-thrust bearing and the laminar flow assumption is no longer applicable to the actual operating conditions of the water-lubricated bearings at a high rotation speed. In addition, optimal micro groove depths for both journal bearing and thrust bearing exist to reach the peak of the load capacity while the optimal micro groove depths for journal bearing and thrust bearing are not the same.