Ocean tide energy water turbine

The invention relates to an ocean tide energy water turbine and solves the problem of high impeller height requirement of an existing water turbine for sea-surface impeller power generation. The ocean tide energy water turbine comprises an electric generator. The electric generator is connected with an impeller immersed in seawater. The ocean tide energy water turbine is characterized in that the surface of the impeller is uniformly provided with a plurality of V-shaped grooves; the V-shaped grooves extend to the axial direction; each V-shaped groove is provided with a blade capable of being buckled/ unfolded through swinging; a swing shaft of each blade is arranged along the groove bottom of each V-shaped groove; the two side walls of each V-shaped groove are a buckling surface and an unfolding surface respectively; the included angle between the unfolding surface and the impeller in the radial direction is smaller than the included angle between the buckling surface and the impeller in the radial direction; when the blade is fitted to the buckling surface, the radial distance of the outer end of the blade and the center of the impeller is the smallest; and when the blade is fitted to the unfolding surface, the radial distance of the outer end of the blade and the center of the impeller is the largest. The ocean tide energy water turbine adopts the blades which can be buckled and unfolded under the driving of ocean current, so that the impeller of the water turbine can adapt to the ocean current of any direction to carry out power generation.