Adjustable quantitative pipetting device

The invention discloses an adjustable quantitative pipetting device. The device comprises a pipe body, a push-pull rod and a cover body, the cover body is positioned above the pipe body, the push-pullrod penetrates the cover body and is positioned in the pipe body, the lower end of the push-pull rod is provided with a piston matched with the size of the inner wall of the pipe body, the upper endof the push-pull rod is provided with a handle, a bracket at the middle part of the push-pull rod comprises a plurality of partition plates in the vertical direction, the partition plates are positioned on the same circumference, a limiting plate in the horizontal direction is arranged between adjacent partition plates, and the limiting plate is fan-shaped; and the pipe body is of an integrated structure, the lower end of the pipe body is provided with an opening, the upper end of the pipe body is provided with an annular projection, a limiting ring on the outer side wall of the annular projection is matched with and c