The invention discloses a constant-
power control method and device for the full-load power generation working condition of a wind 
turbine generator, and the wind 
turbine generator. The constant-
power control method for the full-load power generation working condition of the wind 
turbine generator comprises the 
pitch variation operation step and the 
electromagnetic torque variation operation step. The 
pitch variation operation step includes that the 
electromagnetic torque difference of the generator is calculated according to the current rotating speed of the generator; the 
gain used by PI correction is determined according to a current 
blade pitch angle, and the PI correction is carried out on the 
electromagnetic torque difference of the generator to obtain a compensation value of the 
pitch angle; a given value of the 
pitch angle is added to the compensation value of the 
pitch angle, 
pitch variation operation is carried out on the basis of the 
pitch variation rate converted from a required value, obtained through addition, of the 
pitch angle. The electromagnetic torque variation operation step includes that electromagnetic torque variation operation is carried out on the basis of a required electromagnetic torque value which is obtained by dividing the rated power of the generator by the current rotating speed of the generator. According to the constant-
power control method and device for the full-load power generation working condition of the wind turbine generator, under the full-load power generation working condition, the 
blade pitch angle is adjusted on the basis of pitch angle compensation, the rotating speed of the generator can be more stable, the electromagnetic torque variation operation is carried out on the basis of the 
pitch variation operation, 
power fluctuation of the generator is reduced, and constant-power control is achieved.