The invention provides a mechanical rotating speed control device and wind power generating equipment. The wind power generating equipment comprises a wind wheel, a generator and an energy storage device, wherein the wind wheel can be used for receiving wind energy to rotate; the generator is provided with an input rotating shaft which can rotate under kinetic energy from the wind wheel; the energy storage device is positioned between the wind wheel and the generator and enables the input rotating shaft of the generator to acquire stable rotating speed input; a rotating speed control device is arranged between the generator and the energy storage device and comprises a first rotating member and a second rotating member; the first rotating member can be connected with the motor so as to be driven by the motor to rotate according to preset rotating speed; and the second rotating member is meshed with the first rotating member and connected with the input rotating shaft of the generator. Compared with traditional wind power generating equipment for realizing constant speed and constant frequency by using power electronic equipment, the wind power generating equipment can realize constant speed and constant frequency output at lower cost.