Computational fluid dynamics (CFD) has been used to study the boundary layer flow around 4 different bottom-fixed offshore wind turbine foundation designs. A large region of down flow exists in front of the foundation, which causes the backflow. Pressure distributions around the foundations were studied. A positive vertical pressure gradient(dp/dz > 0) was found in front of the monopile foundation. A larger volume of increased pressure exists in front of the monopile foundation than in front of the gravity-based foundations due to the geometry. The horseshoe vortex was found in front (upstream side) of the 4 kinds of foundations. One horseshoe vortice was found in front of the monopile foundation, two were found in front of the other gravity-based foundations. The bed shear stress in the flow direction along the upstream symmetry line(y/D = 0, z/D = 0, -10 < x/D < 10) on the seabed was investigated. As a conclusion, the hexagonal Gravity-Based-Foundation was found to have a better behavior than monopile and 2 other gravity-based foundations.