A navigation device with power saving mechanism and method thereof are provided. The navigation device includes a global positioning system (GPS) receiver, a first processing unit, a second processing unit and a sound playing unit. The GPS receiver produces a longitude-latitude information by receiving a satellite signal from the GPS. The first processing unit switches from a first mode to a second mode according to a control signal. Then, the first processing unit is disabled after switching. When the second processing unit is enabled, a direction information and a distance information are generated by comparing the longitude-latitude information with a destination information. The sound playing unit selects two frequencies among a plurality of navigation frequencies according to the direction information and the distance information, and plays the tone signals which are comprised of the two frequencies in sequence.