Provided are a blade driving method, a blade driving device and an air conditioner indoor unit. In the blade driving method, blade drive motors are driven, the power of the blade drive motors is transferred to two or more output side gears through input side gears and then transferred to a plurality of blades connected with the two or more output side gears, and therefore the blades are driven to rotate. According to the blade driving method, the blade driving device and the air conditioner indoor unit, the blade drive motors can be utilized for synchronously driving the two or more blades, the number of blade drive motors can be reduced, and therefore drive control over the blades can be effectively simplified. In addition, due to the fact that the power of the motor is transferred through the gears, control precision can be improved.