Urban traffic state analysis plays an important role in the solution of traffic congestion problem. To identify traffic state effectively is a foundational work for improving traffic condition and preventing traffic congestion. In this paper, an index system of traffic state was established, it through analysis of the multi-source and heterogeneous data from the traffic network, and for the demand of complex structure of large-scale road networks. The proposed index system includes micro-layer, which describes flow tendency on links or nodes, and meso-layer, which represents link-to-link or given region flow condition and diversification, and macro-layer, which indicates more large-scale than meso-layer region flow status and variety. A new method of estimating level of service (LOS) of link, node and network is developed to identify traffic state. A numerical example is studied in Stabilized-door bridge to Bell-tower bridge urban traffic. The proposed index system is employed in evaluating traffic level of service to get traffic flow condition and variety. The evaluation results show that level of service can truly reflect the traffic state. Accordingly, the truly traffic status testified the effective for the proposed evaluation method in traffic level of service.