The invention discloses a TCSC emergency control method for improving the transient stability of a power system. The method comprises the steps of firstly judging whether TCSC emergency control is started or not; if so, sending out a forced compensation command to a TCSC by security control after clearing a fault, or else, completing the method; calculating a rotor angle, an angle velocity, an inertia time constant, electromagnetic power and mechanical power of an equivalent machine; calculating currently accumulated acceleration energy and deceleration energy of the equivalent machine; determining a TCSC emergency control strategy according to the currently accumulated acceleration energy and deceleration energy of the equivalent machine; and judging whether to exit from the TCSC emergency control strategy or not, if so, restoring an original TCSC control strategy, and or else, returning to TCSC emergency control in the next oscillating period. According to the TCSC emergency control method for improving the transient stability of the power system, the stability margin of a first swing in the transient process can be effectively improved, damping control of subsequent oscillation can be achieved, and power angle and power oscillation can be quickly calmed down.