Abstract: With the expansion of the power grid and the large-scale access of power users, voltage transients caused by faults in transmission and transformation equipment and electrical equipment have become increasingly frequent. By simulating and analyzing voltage sag, the residual voltage of the power supply bus of sensitive equipment after voltage sag occurs is studied, and the voltage sag immunity of sensitive loads is evaluated. Reasonable selection of voltage sag control measures for insufficient voltage sag immunity can not only effectively solve the problem of sensitive load disconnection caused by voltage sag, but also have significant implications for improving the relationship between power supply and consumption.