Aiming at transient overvoltage problem of Alternating Current (AC) system after Ultra-High Voltage Direct Current (UHVDC) system blocking, surplus reactive power after UHVDC system blocking and short circuit capacity are deduced, and the relationship between these two parameters and transient overvoltage of AC system are analyzed in detail. Subsequently, the influence on AC system transient overvoltage exerted by timing sequence of wind turbines tripping by safety and stability control system and filter tripping by pole control system is analyzed contrastively. A stability control scheme based on wind turbine Fault Ride Through (FRT) capability and the corresponding transient overvoltage suppression strategy are proposed. Lastly, a simulation model of power grid in Hami is established based on DIgSILENT experiment platform to verify the validity and feasibility of the proposed stability control scheme and transient overvoltage suppression strategy. Simulation results verify that the proposed stability control scheme and transient overvoltage suppression strategy can reduce transient overvoltage effectively, avoid the risk of wind turbines cascading trip-off, and promote voltage recovery of AC system. This work is supported by National Natural Science Foundation of China (No. 51877185).