Aiming at the transient overvoltage problem in the new energy high-penetration area of the feeder due to DC bipolar blocking fault, a converter bus reactive power allocation capacity optimization scheme is proposed with the constraint that the transient overvoltage of the wind farm with the lowest safety margin in the feeder system is suppressed to below the target value. On this basis, a cutting scheme for suppressing transient overvoltage in the feeder system under bipolar blocking faults is proposed, which realizes the two-stage voltage stabilization control of the feeder system by prioritizing the cutover of wind turbine generators without high-voltage ride-through capability after the occurrence of faults. Finally, a simplified model of ±800 kV Tianzhong DC transmission system and its feeder grid is constructed based on the DIgSILENT simulation platform. The simulation results show that the proposed reactive power optimization allocation scheme and machine-cutting scheme can reduce the transient overvoltage of the target node by 0.12 p.u., and the accuracy can reach 95.56%. The proposed scheme has significant effect in suppressing the transient overvoltage caused by DC blocking, which can effectively prevent the new energy from large-scale chain off-grid and improve the stability and reliability of the system.