The invention relates to a motor control device and a motor control method, mainly used for judging whether a motor is in a back pressure area or not so as to respectively provide different rotate speed control signals of the motor. When a fan is in a low working period, a first circuit is used for control so as to ensure that the fan has more accurate rotation speed; when the fan is in a high working period, a second circuit is used for control so as to ensure that the rotation speed of the fan can not be limited when the fan enters the back pressure area, and the fan can have better wind pressure and wind amount.