According to the transient instability detection method based on the perturbed voltage trajectories，methods for wide-area monitoring scheme designing and instability threshold setting are discussed.Besides，the applicability and feasibility of the proposed method in the actual application process are analyzed.Numerical simulations are conducted for an IEEE39-bus system and an actual power system of China Southern Power Grid，including the vulnerability analysis of bus voltage，voltage observation scheme design and transient stability detection under different fault conditions.Compared with conventional methods，the simulation results show that the proposed method can more effectively and quickly identify the transient instability of the system，and is easy to apply in projects.This method can be used for an incomplete wide-area measurement environment.