The invention discloses an adjusting method for gear separating operation of a power station fan. The adjusting method comprises the following steps that 1, gears of gear separating operation of the fan are classified according to the operation rotating speed ni of the fan; 2, the number N of the gears of gear separating operation of the fan is determined according to the operation state of the fan; 3, according to operation economy and safety of the fan at each gear, the actual operation rotating speed ni of each gear and the adjusting ranges alpha1 to alpha 2 of the angles alpha of blades/baffles are determined, and the adjusting ranges of the angles alpha of the blades/baffles of the gears are the same; 4, when the fan is switched from the high gear to the low gear or switched from thelow gear to the high gear, the operation rotating speed ni of the fan and the angles alpha of the blades/baffles are switched synchronously, after switching is completed, the operation rotating speedni of the fan is kept unchanged, and only the angles alpha of the blades/baffles are adjusted. According to the method, gear separating operation of the fan is achieved by adjusting the rotating speedof variable rotating speed drive equipment, the operation efficiency of the fan under the working condition with the medium and low loads is improved, and then the operation performance of the fan onthe full-load working condition is improved.