Abstract: The invention discloses a navigation system and a method for planning a route thereof. The navigation system includes a storage unit and a processing unit. A cloud database of a cloud server and a local database of the navigation system are allocated in the storage unit, which is configured to store road condition data. The processing unit is connected to the storage unit, and generates an initial route according to an initial location and a destination. The processing unit also compares, computes and analyses the initial route and the road condition data, corresponding to at least one road section of the initial route, stored in the storage unit to generated a plurality of reference routes. Next, one of the reference routes is selected as a final route.