Abstract: With the rapid development of UHVAC and UHVDC projects, a large-scale UHVAC/DC hybrid power grid with close-coupled AC and DC power grids, mutual multi-DC and multi-AC power systems, gradually integrated transmitting and receiving regions, as well as complex and changeable control has been formed in China. To maintain such a complex power grid in the stable and safe states, it is indispensable to study and simulate the operation of the above-mentioned power grid. Until now, all the existing power grid simulation tools cannot complete this challenging work suitably because of the UHVAC/DC power grids having more requirements for simulation tools in the simulation scale, accuracy and speed. In view of this situation, the design scheme of new generation UHVAC/DC power grid simulation platform (NGSP) is proposed in this paper, and the detailed operating functions and architecture of NGSP are also presented and analyzed from the view of the design purpose, technical route and implementation. Based on the proposed design scheme, NGSP can realize the 6000-nodes digital-analog hybrid electromagnetic transient simulation. Meanwhile, compared with the traditional tools, the full-digital simulation acceleration ratio of NGSP has be improved more than 3000, which significantly improves the simulation accuracy and efficiency of large-scale UHVAC/DC power grid of China. Based on the above advantages of NGSP, the simulation technology of China can support the actual development of the power grid now.