A key assembly, which includes a support plate, a flexible circuit board, a buffer block, and a pressing assembly. The support plate has a first surface and a second surface that are opposite to each other. The support plate has an accommodating portion that is recessed from the first surface to a side of the second surface, and the accommodating portion limits an accommodating groove. The flexible circuit board is superposed on the first surface, and the flexible circuit board has a through hole that is correspondingly connected to the accommodating groove. The buffer block is disposed in the accommodating groove, and passes through the through hole. The buffer block has a buffer support surface that protrudes from the flexible circuit board away from one side surface of the support plate. The pressing assembly includes a keycap, a support mechanism, and a connecting rod.