In order to overcome the shortages of model predictive emergency voltage control method which is based on the existing trajectory sensitivities， exponential reference trajectory is introduced. This paper considers the effects of initial state changes on trajectory sensitivities at the post-fault sampling points. The control increment is estimated according to full process dynamic voltage simulation and then the trajectory sensitivities are corrected at the post-fault sampling points. Thus the corrected trajectory sensitivities are close to the actual trajectory sensitivities. Furthermore， the dynamic selecting strategy of control components considering the control cost is formulated in order to satisfy fast control requirements under emergency condition. Results on New England 10-machine 39-bus system demonstrate the feasibility and effectiveness of the corrected trajectory sensitivity method and selecting strategy of control components.