A thin keyboard structure includes a circuit board and a keycap assembly board located on the circuit board. The circuit board has a plurality of command portions to receive contact and generate command signals. The keycap assembly board has a frame with a plurality of press zones corresponding to the command portions. Each press zone has at least one press portion corresponding to one command portion and depressible to move towards the command portion. Each press zone also has a deformation portion centered on the press portion and coiled and extended continuously from the press portion towards the frame at a preset interval to provide deformation and return force for the press portion during movement towards the command portion. The press portion and deformation portion replace the driven mechanism used in the conventional keyboard, hence total thickness of the keyboard can be reduced to make the keyboard thinner.