A method and a system for power saving and state retention in an electronic device are provided. The method for power saving and state retention in an electronic device includes recording a state variation of electronic components of a plurality of groups in a second circuit of the electronic device in a variation table stored in memory of a first circuit or the second circuit of the electronic device; before stopping providing power to the second circuit, selecting some groups from the plurality of groups according to the variation table and making a backup of states of electronic components of the selected groups; and after restoring power to the second circuit, restoring the states of electronic components of the selected groups according to states in the backup.