The network layout is the basis of transportation operation and the connectivity degree is one of important indexes to evaluate the network structure. When mapping out and selecting the comprehensive transport network planning scheme, in order to judge the connectivity of network, for its topological structure being composed of different modes of transport lines with the characteristics of complex graph, the counting of spanning tree in graph theory is applied to analyze the network connection quality. At the same time, to examine and evaluate the influence of the edges between nodes on the entire network connectivity, the calculation model of edge influence degree is proposed in terms of the changes in the number of spanning trees after removing one of edge as well as considering the traffic capacity, function and administrative status of links. The method based on spanning tree combined with traffic attributes is simple and easy to operate, and the example illustrates the effectiveness. It can provide decision-making basis for the evaluation and comparison of connectivity performance of comprehensive transport network layout schemes.