The invention provides a motor starting control method, device and an air conditioner, and relates to the technical field of air conditioners. The motor starting control method and device are used forgiving the duty cycle according to the preset duty cycle change rate when the starting instruction is received, and a actual value of the rotation speed of a PG motor is obtained in real time; when the actual value of the rotating speed is greater than or equal to a preset threshold value of the rotation speed of a first motor, the current duty cycle is obtained, then the current duty cycle is taken as an initial value, and the duty cycle is given based on the threshold value of the rotation speed of the first motor, the preset target rotation change rate and an actual value of the rotation speed; and finally, when the actual value of the rotation speed is greater than or equal to the preset target rotation speed value, the duty cycle is given based on the actual value of the rotation speed and the target rotation speed value. The motor starting control method and device divide the start-up process of the PG motor into three stages, the steady change of the duty cycle of the output ofa PI regulator is ensured during the switching stage, so that motor rotation speed is enabled to be steadily changed and not abrupt, and a fan is enabled to run smoothly.