Small molecule separator

The utility model discloses a small molecule separator which comprises a top (1), at least one additional section (2) and a bottom (3) which are movably connected in sequence from top to bottom, a first membrane area (4) is arranged between the top (1) and the additional section (2), a second membrane area (5) is arranged between the additional section (2) and the bottom (3), and a third membranearea is arranged between every two adjacent additional sections (2); wherein the top (1) is a straight cylinder, the bottom end of the top (1) is provided with a first connecting area (6) used for being connected with the top end of the increasing joint (2), the top end of the first connecting area (6) is detachably connected with the first membrane area (4), and a sample adding area is arranged above the first membrane area (4). The device can be used for separating and purifying proteins or medicines, the separation time can be shortened, the activity of the separated proteins or medicines is not influenced, and the