1. A keypad assembly having three-dimensional patterns, comprising: a bottom layer; a light-guiding plate overlapped on the bottom layer; a pattern layer provided on the light-guiding plate, the pattern layer being provided thereon with a plurality of three-dimensional patterns; a coating layer coated on an upper surface of the pattern layer; and a surface layer overlapped on the coating layer, the surface layer being formed with a plurality of keycaps to correspond to the three-dimensional patterns.