The invention discloses a liquid quantitative acquisition device and belongs to the field of medical apparatuses. The liquid quantitative acquisition device comprises an acquisition part and a collection part. The acquisition part comprises a handle part, an acquisition cup and an acquisition cylinder. The handle part is connected to the acquisition cup or the acquisition cylinder. The bottom of the acquisition cup is connected to the top of the acquisition cylinder. The bottom of the acquisition cup is provided with an overflow orifice. The top of the acquisition cylinder is provided with a liquid inlet valve which automatically closes an inlet at the top of the acquisition cylinder after the acquisition cylinder is filled with the liquid. The bottom of the acquisition cylinder is provided with a normally closed drain valve. The collection part comprises a drainage cap and a collection pipe. The drainage cap is arranged at the opening of the collection pipe. The drainage cap fits to the bottom of the acquisition cylinder so that the normally closed drain valve is opened. Through use of a method comprising quantitative acquisition and collection in an order and enclosed management of the acquired liquid, human body, environment and equipment pollution is avoided, medical staff-caused physical and psychological health influence and damage in liquid displacement is thoroughly avoided and acquired liquid originality is guaranteed.