The invention discloses a plasma collecting system for optimizing amount of anticoagulant, comprising a blood pump for driving blood to flow in the tube； an anticoagulant pump for driving an anticoagulant to flow in the tube； an HCT testing device for testing the blood HCT content； a calculating device for calculating a mixing ratio of the anticoagulant to whole blood according to the blood HCT content； and a control device for calculating the rotational speed ratio of an anticoagulant pump to a blood pump according to the mixing ratio of the anticoagulant to whole blood and a flow ratio of the anticoagulant pump to the blood pump. The required anticoagulant dosage is calculated by means of measuring the blood HCT content of every plasma donor to obtain the optimal anticoagulant dosage. The optimization is beneficial to the health of the plasma donor and to improving the quality of collected plasma. Meanwhile, the non-intrusive method of testing the blood HCT content introduces no contamination to the plasmapheresis and provides reliable basis for precision control of the anticoagulant dosage.
