The invention relates to a movable blade tip winglet for a wind turbine blade and belongs to the field of wind power generation. The top end of the wind turbine blade is connected with the movable winglet; a steering engine is connected with a driving rod which is connected with a booster; and the booster drives the movable winglet to rotate. The invention aims at providing the movable winglet device for the wind turbine blade, which can be used for controlling the flowing of a blade tip part, reducing the aerodynamic load at a high wind speed under the condition of maintaining the aerodynamic efficiency of the blade at a low wind speed, and stably and accurately controlling the aerodynamic load nearby a rated wind speed and the generated power so that the aerodynamic load applied to the blade and the whole generated power can be in smooth transition.