A control method and a control system (2), by which a motor (31) can be controlled. The control system (2) comprises a central processing module (22) and a drive control module (23). In a period in which a voltage is not applied to any phase coil of the motor (31), the drive control module (23) collects voltages of the coil to which the voltage is not applied, and converts the voltages of the coil into digital signals. The central processing module (22) reads the digital signals and determines whether the running speed of the motor (31) is consistent with a preset speed depending on whether an average value of the digital signals falls within a preset threshold range, which helps to improve the control precision.