The available space-vector of a Vienna topology is affected by current, which makes the connection problem during the switching between switching sequences under discontinuous space-vector modulation become more serious. To explore the mechanism of connection problems and reduce their impact, the possible situation under the switching between switching sequences when current does not change is analyzed at first. Then, the vector synthesis error caused by the lag or lead deviation between the ideal and actual sectors when current changes is deduced. On this basis, an optimization strategy for selecting a specific switching sequence before and after switching is given. In addition, the connection problems in several common discontinuous vector modulation schemes are analyzed, and an optimization scheme is given in combination with the proposed optimization strategy. Finally, simulation and experimental results verify that the optimized scheme can achieve a smooth connection of switching sequences, and the corresponding optimization strategy is simple to implement and has certain practicability.