Abstract: The present invention relates to a water-based coating composition, the preparation and use of the composition, a two-component coating system comprising the composition and use thereof, and an article obtained by coating with the composition or the two-component coating system. The water-based coating composition comprises a water-based UV resin; a silane-treated nanosized silicon oxide compound; and a photoinitiator; wherein per kilogram of the solid constituent of the water-based UV resin contains not less than 3 mol of ethylenically unsaturated groups, and wherein the weight ratio of the solid constituent of the nanosized silicon oxide compound to the solid constituent of the water-based UV resin is 11:20 to 73:100. The coating layer formed by the water-based coating composition of the present invention has high hardness and good adhesion, and is particularly suitable for electronic, electrical and communication equipment in the 5G field.