With optical networks evolving to the next generation optical networks, various services are intended to be carried over a single optical network infrastructure. This contributes to the phenomenon that different services with different QoS requirements may survive in a set of degradative network working-states. Thus during the study of optical network reliability, it is insufficient to regard optical networks as having only binary working-states according to their network connectivity. We proposes here a new reliability evaluation model for WDM networks, which regard the network as a system having multiple working-states with reference to their route (s-t) capacity and maximum hop number constraints. Additionally, considering that there exist in WDM networks some elements whose failures affect neither the nodes nor the entire links but only certain wavelength channels in the links, a new kind of network element is added to the traditional element types (nodes and links) of network reliability evaluation model, namely wavelength channel related elements. The model was used to simulate the reliability of WC (wavelength continuous), PWC (partial wavelength conversion) and NWC (non-wavelength continuous) WDM networks with CERNET topology by way of Monte-Carlo method. Simulation results indicate that different working-state requirements may lead to different reliability evaluation results, and the differences will enlarge very quickly with the increasing of network element failure rates. This implies that the study of WDM network reliability should be performed under multiple working-states assumption, especially for multi-service networks, and the addition of the new network element kind - a wavelength channel-related element is necessary.