For large-scale renewable energy UHVDC transmission system, fault happens on the receiving end may cause drastically change on the sending end power grid, which seriously threatens the stability of the sending end power grid. Therefore, voltage characteristic of the sending end is an important consideration for the adaptability of the HVDC transmission system. Hybrid HVDC combines the advantage of LCC-HVDC and VSC-HVDC. In view of the application scenario of large-scale renewable energy transmission through hybrid HVDC, this paper first introduces the typical topologies of two-terminal HVDC transmission system. The corresponding mathematical model is established and the basic control structure is also expounded. Then the AC voltage characteristics of the sending end power grid when short-circuit fault occurs in the receiving end under different hybrid HVDC topologies are analyzed. Finally, the simulation model of different hybrid HVDC topologies is established in the PSCAD/EMTDC simulation platform, and the effectiveness of the above analysis is verified. This work is supported by Science and Technology Project of the Headquarter of State Grid Corporation of China (No. B3440817K003).