Disclosed a system and method of lengthening a life span of a battery power supply in an appliance such as a portable appliance, notebook computer or the like. A power saving method in an appliance includes displaying a user set-up menu for a power saving on a screen by respectively checking systems in the appliance, outputting a control command to a micro-controller in accordance with power saving contents determined on the user set-up menu by a user, and executing a power saving program set up by the user in accordance with the control command of the micro-controller.