Abstract: Based on the Lyapunov-Krasovskii functional stability theory analysis method, the stability problem of delayed power systems with PID parameters in the system matrix is discussed. Firstly, the mathematical model of delayed power system with PID parameters is analyzed and constructed. Secondly, a new stability criterion is derived by constructing a delay-product-type Lyapunov-Krasovskii functional and an extended inverse convex quadratic inequality method is applied to define the inverse convex terms in the derivatives of the functional. Finally, experimental simulations are conducted using numerical example to analyze the relationship between the PI control gain and the system time delay stability margin under constant and time-varying delays. The experimental simulation results show that the stability criterion proposed has obvious advantages over other similar works.