With the advent of large-scale hybrid AC-DC grids, electromagnetic transient (EMT) simulation is required to accurately describe the dynamics of systems. However, EMT steady-state initialization for hybrid AC-DC systems is difficult and time consuming when the system scale is very large. To provide a stable snapshot for EMT simulation with nonlinear components and black-box components, this paper proposes a general initialization scheme for EMT simulation (EMT-GIS) that can be implemented in electromagnetic transient program (EMTP)-type simulators. First, an integrated power flow (IPF) algorithm is introduced to provide steady-state results. Then, an initialized snapshot calculation-and-splicing mechanism is designed for EMT-GIS. The proposed EMT-GIS is tested using a hybrid AC-DC system in China on the CloudPSS simulation platform. Test results verify the effectiveness of the proposed EMT-GIS.