The invention relates to a speed changing system for a wind power heating device. Two discs for driving are arranged in a cavity respectively and connected with wind turbine blades and a stirring barrel respectively through shafts, when the disc which is connected with the wind turbine blades rotates to a certain rotating speed, the disc which is connected with the stirring barrel is driven to rotate under the action of fluid viscosity, and a fluid in the stirring barrel can be heated. The distance H between the two discs is 1-3mm and opposite surfaces of the discs are provided with blades. According to the speed changing system for the wind power heating device, the shaft of the disc which is connected with the wind turbine blades rotates to heat water in the cavity, when wind power is increased, the disc which is connected with the wind turbine blades can drive the disc which is connected with the stirring barrel to rotate, and a stirring plate in the stirring barrel can be driven through the shafts to heat the fluid. Therefore, flexible starting and simultaneous heating can be achieved, especially, the fluid in the cavity can be heated, and the two discs are slightly close so that the heating efficiency is high under extremely high friction function. When wind power is increased, the shafts drive the stirring barrel for heating, and therefore, loads are adjusted and wind energy can be fully utilized.