A plasma collecting system for optimizing an amount of an anticoagulant, comprising: a blood pump for driving blood to flow in a line； an anticoagulant pump for driving an anticoagulant to flow in a line； an HCT test device for testing the content of HCT in blood； a computing device for computing, according to the HCT content in blood, a mixing ratio of the anticoagulant to whole blood； and a control device for computing, according to the mixing ratio of the anticoagulant to whole blood and a ratio of the flow of the anticoagulant pump to the flow of the blood pump, a ratio of the rotational speed of the anticoagulant pump to the rotational speed of the blood pump. By testing the content of HCT in blood of each plasma donor to compute the desired amount of an anticoagulant, the aim for an optimum amount of an anticoagulant is achieved, thereby facilitating the physical health of the plasma donor and facilitating improving the quality of the collected plasma. In addition, the content of HCT in blood is tested noninvasively, without causing any pollution to plasmapheresis, and can provide a reliable basis for the precise control on the amount of the anticoagulant.
