Abstract: With advancements in the construction of new power systems, the operating mechanism and dynamic characteristics of these systems have become increasingly complex, and the randomness of the power grid has increased. Power-angle and voltage stabilities are often intertwined and difficult to distinguish, hindering the formulation of accurate and effective control strategies. Therefore, accurately identifying the system stability of the main guidance mode is crucial for power grid regulation. First, this study analyzed the dialectical relationship between power-angle and voltage stabilities of the power grid. Second, taking the voltage phasor trajectory as the starting point, the geometric characteristics of the phase trajectory and its trajectory-sensitivity mathematical model were analyzed. On this basis, quantitative analysis was conducted based on the trajectory-sensitivity distance to determine the dominant characteristics of power-grid static stability, and a criterion for identifying the dominance of this stability based on voltage phasor trajectory was established. Finally, through case analysis and comparative verification, the effectiveness of the proposed method was verified, and the dominant pattern recognition of power-grid static stability was established.