A maximum power point tracking method, applied to a tracking device, employs a DC/DC converter connecting with a solar cell array, and including a controller actuating the DC/DC converter to perform an active resistance characteristic; a maximum power point tracking circuit adjusting the active resistance of the DC/DC converter; monitoring a change of an output power of the solar cell array in determining a direction for adjusting the active resistance of the DC/DC converter; and the maximum power point tracking circuit repeatedly adjusting the active resistance of the DC/DC converter. If the change of the output power of the solar cell array is positive, the active resistance of the DC/DC converter is adjusted in the same direction; but, conversely, if the change of the output power of the solar cell array is negative, the active resistance of the DC/DC converter is adjusted in an opposite direction.