Eventhough voltage stability is a dynamic problem, static indexes are still important parameters in voltage stability analysis. Some important voltage stability indexes are reviewed and a comparison of their performance under dynamic load is given in this paper. The advantages and disadvantages of each index are demonstrated. Some of the indexes are found to be equivalent to each other. The effectiveness of these indexes is demonstrated through two case studies in IEEE 39-Bus New England System under dynamic load. An agreement with the theoretical analysis is shown by the simulation results.