A navigation device capable of displaying the public transportation service and method thereof are disclosed. The navigation device comprises a navigation module and a map database. The map database is for storing at least one digital map and the frequency of runs and the route forming the at least one public transportation service. The navigation module is for providing a navigation function and displaying the digital map and the route forming the public transportation service on the digital map for indication. The route is displayed by a different color, a different shape of the icon, or a different level of transparency, for the public transportation service having different frequency of runs.