An electronic device and an equalizer adjustment method thereof for adjusting gain settings of an equalizer according to the volume of the output signal are disclosed. The method includes the steps of: setting a volume gain value table including a plurality of volume values through a gain value setting module, which are a first volume value to an Nth volume value with volume incrementally increasing, each of the plurality of volume values including a set of correction parameters which including a plurality of compensation gain values corresponding to a plurality of target frequencies, respectively; storing the volume gain value table in a storage module; obtaining a volume of the output signal; loading the volume gain value table according to the volume of the output signal to obtain the corresponding set of correction parameters; and adjusting gain value settings of an equalizer for different frequencies of sound.