The first ±800 kV UHVDC transmission project of Jiangxi Power Grid is planning to be built in 2020. The large scale of renewable energy in Southwest China will be input into Jiangxi Power Grid through UHVDC, thus, the safety and stability of Jiangxi Power Grid will face challenges. In order to study the influence of receiving side AC system’s fault on the transient stability of AC/DC hybrid system, this paper proposes an offline simulation analysis method, which covers the influence analysis of possible commutation failure, blocking and continuous commutation failure of AC/DC hybrid system. Moreover, the appropriate safety and stability control measures are proposed based on the analysis. Taking the Yazhong-Jiangxi ±800 kV UHVDC transmission project as an example, the two types of faults of DC valve direct locking and continuous commutation failure are analyzed. The effects of two types of faults on the safe and stable operation of Jiangxi Power Grid are compared. The corresponding response measures are proposed. Simulation results show that the proposed method in this paper can effectively guide the operation and control of the power grid, and the proposed safety and stability control measures can effectively improve the ability of the power system to respond to emergencies. This work is supported by National Natural Science Foundation of China (No. 51577075).