Three-dimensional water flow fields at a pyramid artificial reef with three meters high and three meters long of each side of the base were numerically simulated using CFD approach under the five different incoming velocities (0.1,0.2,0.4,0.6and 0.8meter per second respectively). The maximum upwelling height, the maximum and average velocities of the upwelling current as well as the size of wake vortex region were all obtained quantitatively. The paper revealed the characteristics of distributions of vorticity and pressure around the pyramid reef and obtained the hydrodynamic forces and drag coefficients. Moreover, it compared the discrepancies of pyramid reef with a rectangular reef and a three-prism reef in the quantitative characteristic of upwelling and wake vortex region current.