This paper summarizes the essentials of power system dynamic behavior， the characteristics and difference index of disturbed trajectories. The model verification and parameter identification methods，which are based on difference index of disturbed trajectories， are reviewed， together with the existing problems and possible approaches. The index should not only be based on conventional signal processing technologies， but also it should reflect the physical mechanisms of the system dynamics. It is revealed that there exist multi-solution phenomena in multi-parameter identification， thus the identification results depend on both the initial value and search strategy. This problem would be solved with applying multiple sets of measured response curves as benchmarks in different scenarios， and the objective parameters should remain unchanged during the process of calculating these benchmark curves.