This paper analyzes data differences among different scale road networks and points out that topology matching is improper in multi-scale road networks. In order to build relation among identical entities from different scale road networks, this paper concludes that geometry matching, attributes matching and composite matching methods should be adopted. Because a great amount of uncertainties exist during the matching process, selecting appropriate matching thresholds is difficult. In order to avoid selecting accurate thresholds for each matching indicator, this paper proposes a probabilistic theory-based route matching method, which calculates the matching probability through fusing a variety of criteria. The test experiments show that this method acquires better matching effects.