The utility model discloses a screw clamping and loosening device which comprises an assembling mother board (4), an upper clamping plate (5) and a lower clamping plate (6). The assembling mother board (4) is provided with accommodation holes (7) which are distributed in an array mode and used for accommodating screw heads. The upper clamping plate (5) is provided with assembling through holes A (8), and the lower clamping plate (6) is provided with assembling through holes B (12). The left side and the right side of the assembling mother board (4) are respectively provided with an installation block (13), and upper and lower clips (14) on the lower clamping plate (6) and the upper clamping plate (5) are arranged in through holes in the installation blocks (13) respectively. The screw clamping and loosening device has the advantages that through moving of the upper clamping plate and the lower clamping plate, switching between small hole combination and big hole combination can be achieved, furthermore, the switching between the state that screws are clamped and the state that the screws are loosened to be allowed to penetrate through gaskets in a sleeved mode can be achieved, and an installation and clamping device is provided for batches of screws to penetrate through the elastic gaskets and flat gaskets in a sleeved mode.