The continuous grid-connection and formation of ultra-high voltage AC/DC interconnected power grids increase the risk of transient frequency stability events of power system. In high penetration of new energy scenarios, one of the most efficient methods to improve the frequency stability capability of the power system is to enhance the frequency regulation capability of the synchronous generators. Firstly, through the trajectory sensitivity, the dominate parameter which influences the maximum frequency deviation was analyzed, and then it is optimized to improve the transient stability of the power system. The mathematical model of the dominate parameters optimization problem was established. The effect of dominate parameters on the maximum frequency deviation was analyzed analytically, and the nonlinear optimization problem was approximated with a linear programming problem according to the sensitivity analysis method to reduce the calculation load. On this basis, an optimization method of adjustment coefficient for multi-machine power systems was proposed. Finally, the effectiveness of this method was verified by simulation examples.