NOVELTY - The present invention is a method to use to use the fluctuation of sea wave as the power to directly generate electricity, which is to set up the electricity generation system on the offshore sea bed. The system at least comprises: several sea bed bases, several foundation piles, a large floating board, a fixing frame for electric generator, a power transmission shaft, at least an electric generator, and electrical power t transmission line. The foundation piles are fixed to the sea bed, the height of the foundation piles must be higher than the sea surface so as not to be impacted by sea wave. A fixing frame is installed on top of the foundation piles for the electric generator to be fixed and placed on. The large floating board has plural fitting hole for fitting on the foundation piles, so that the large floating board can fluctuate with the height undulation of sea wave on the sea. A power transmission shaft is installed vertically on the floating board. By the longitudinal gear rack of the power transmission shaft, the gear on the horizontal shaft of the generator is driven to drive the generator to generate electricity. In order to sufficiently make use of the vertical undulatory power of the large floating board, the electric generator is so designed that it can generate electricity in both forward and reverse rotations; or two generators can be installed, one generates electricity in the forward rotation, and the other one generates electricity in the reverse rotation. To increase the wave amplitude of sea wave for increasing the wave energy and further increase the amount of generated power, a wave-amplifying dike can be installed on the appropriate sea bed at the location where the sea wave electric generation equipment faces the sea, so that the wave on the mild sea bed is suddenly confronted with the wave-amplifying dike to strike upward against the large floating board of the sea wave electric generation equipment instantaneously, thereby increasing the generated electricity. The auxiliary levees arranged in a V-shape expanding outward can be additionally disposed on the left side and the right side of the wave-amplifying dike facing the sea, so that the sea wave can be further concentrated and guided into the large floating board of the electric generator equipment.