Key structure and assembly method thereof

A key structure comprising:

• a base plate comprising an upper surface and a bottom surface and having a first accommodation hole and two second accommodation holes penetrating through the upper surface and the bottom surface;
• a switch disposed on the base plate and passing through the first accommodation hole;
• two fixing bases respectively disposed on the base plate and passing through the two second accommodation holes, wherein each of the two fixing bases has a guiding channel and comprises a plurality of first stopping surfaces facing the bottom of each of the two fixing bases;
• two movable members each disposed in one guiding channel of the two fixing bases, wherein each of the two movable members comprises a body and a plurality of protrusions radially protruded from a side surface of the body;
• and
• a keycap disposed on the switch and two movable members;
• wherein, each of the two fixing bases comprises a first portion protruded from the upper surface and a second portion protruded from the bottom surface, and a projection area of the first portion in a direction perpendicular to the upper surface is not greater than a projection area of the second portion in a direction perpendicular to the bottom surface, and
• when the keycap is located at a non-pressed position, the protrusions lean on the first stopping surfaces.