Consistency assurance mechanism is of particular importance for online software evolution. Different from traditional approaches based on attributed graph grammar or architectural description languages, the paper investigates the problem from the behavioral perspective and proposes a novel verification technique based on hierarchical timed automata. The approach can directly support the modeling of temporal aspects as well as the hierarchical organization of composed systems in open environments. To make it feasible for consistency verification, this paper also proposes a flattening algorithm, translating the model into a set of synchronized serial timed automata so as to be fed into third-party tool-set. An example is presented throughout the paper to illustrate the new method. Experiments are carried out to complement the discussion and demonstrate the feasibility of the proposed approach.