A device for converting wave energy into electricity, the device including: a float; a guiding-accelerating wheel, the guiding-accelerating wheel including a wheel body including a casing, a wheel center, and a chamber; an impeller; and an electric generator, the electric generator including a rotor. The float is upward and downward movable in accord with a movement of wave. The guiding-accelerating wheel is connected to a lower part of the float. The wheel center is disposed inside the casing. A plurality of deflectors is annularly arranged between the casing and the wheel body, and the deflectors are inclined to a same direction. Water channels are formed by the casing, the wheel center, and every two adjacent deflectors, each water channel including a water outlet. The impeller is clamped on the guiding-accelerating wheel at a position corresponding to the water outlet of the water channel.