Ocean current is a primary physical parameter to describe the ocean motion and understand the ocean change, playing a key role in oceanography. Ocean currents have dynamic characteristics of multiple temporal and spatial scales, and their states and simulations are a key part of the climate prediction, being the frontiers of Earth Science and global change research. The direct real-time observations are not available for the global ocean surface current fields so far. Existing ocean dynamics observations mainly rely on satellite altimetry to inverse large- and meso-scale geostrophic currents on hundred kilometers scale based on the geostrophic balance relationship. There is a gap in the observations and research of the global sea surface currents and non-equilibrium processes at scales of less than 100 km. Doppler satellite oceanography is an important way to solve those problems. In this regard, China, Europe, and the United States have proposed the Doppler satellite oceanography satellite concepts. The Chinese Academy of Sciences has proposed the Ocean Surface Current multiscale Observation Mission (OSCOM) to detect the global ocean surface current and conduct research on the ocean multiscale dynamic processes. OSCOM innovatively proposed the Doppler scatterometer (DOPS) measurement principle, which could detect ocean surface current, ocean surface vector wind, and ocean surface wave spectrum (abbreviation: "current-wind-wave") simultaneously. Using DOPS, a real-aperture radar, by a dual-frequency (Ka+Ku) with conically scanned rotating multi-pencil-beam antenna, OSCOM could conduct the integrated observations of "current-wind-wave" with a swath of more than 1000 km and a high-resolution of kilometer spatial scale. OSCOM will break through the research bottlenecks of ocean sub-mesoscale and non-equilibrium dynamics, ocean multi-scale interactions, and air-sea coupling, and support the theoretical research in ocean sciences and climate change. With the launch of the OSCOM, the application of sea surface current observations will improve the numerical model study, laying the foundation for numerical simulation, assimilation, and forecasting of oceanic non-equilibrium dynamical processes, achieving significant improvements in ocean and ocean-atmosphere coupled models. The application of OSCOM current observations, together with the other multi-source satellite dataset, including the high-resolution SST and ocean surface color, will provide support for the research in marine biogeochemical cycles and carbon budget, meeting the need of the national strategy. The implementation of OSCOM scientific satellite is of vital significance to the advance of the study and the application of satellite observations in Earth Science, leading to the implementation of the applied satellites in China.