Abstract: The latest progress in sealing liquid-medium with magnetic fluid was tentatively reviewed.The advantages of the magnetic fluid seal over the conventional ones included "zero" leakage, negligible wear-rate and long service-life.The discussions with specific examples focused on:i) the extensively studied theoretical subjects, for example, the stability at the interface of magnetic fluid and sealed liquid, and the influence of the realistic interfacial properties of the two fluids, such as the viscosity, relative velocity, surface tension and chemical reactions, on the leakage rate;ii) the hot-spot experimental studies, including but not limited to the sealed media of sea-water, lubricant-oil and blood;iii) the structural designs, involving modification, optimization and combination of conventional sealing structures.Moreover, the development trends, potential applications in frontier fields, technical problems and possible solutions were also briefly discussed in a thought-provoking way.