The present disclosure illustrates a motor speed curve control circuit. The motor speed curve control circuit is configured for adjusting a speed of a motor according to a motor speed curve. The motor speed curve control circuit comprises a divider resistor module, an analog-to-digital converter and an arithmetic unit. The resistor module is configured for generating at least one turning-point voltage. The turning-point voltage is used to adjust a slope of the motor speed curve. The analog-to-digital converter converts the turning-point voltage to digital form. The arithmetic unit sets a speed associated with the turning-point voltage corresponding to a first preset duty cycle in the motor speed curve, such that the motor speed curve becomes linear. The arithmetic unit generates a second pulse width modulation signal according to the adjusted motor speed curve and a first pulse width modulation signal to drive the motor.