In-vehicle route guidance systems (RGS) have gained significant popularity worldwide due to their promising potential to reduce many transportation-related problems such as driving-induced stress, congestion, traffic accidents and air pollution. In this paper an implemental way to design the intelligent in-vehicle navigation systems was presented. Some key technologies such as 3D map display, speech interface and dynamic optimal path algorithm, were discussed. At last the navigation software was developed with the combination of MapX, Multigen Vega and Visual C++.