Abstract: The integration of large-scale photovoltaic（PV） and energy storage into power grid has introduced complexity to the transient characteristics of the grid, resulting in diverse transient stability issues. In order to understand the impact of large-scale PV and energy storage on transient stability of power grid, a simulation model of a regional power grid with a large-scale PV and energy storage system is constructed using simulation software, and the effects of different system structural parameters and inverter control parameters on transient stability characteristics of power grid with large-scale PV and energy storage system are analyzed. Firstly, the influence of PV penetration rate and PV-storage capacity ratio on transient stability is investigated for system structural parameters. And then, the impact of PV low voltage ride-through control parameters on transient stability is analyzed for inverter control parameters. On this basis, adjustment measures for control parameters are studied to enhance the transient stability of the system, which can provide an example to refer for the planning and operation of grid-connected PV and energy storage systems.