The work aims to design an automatic filling system based on PLC control for blood type card and apply it to the practical production, so as to solve the phenomenon of generation of air bubbles and wall-hanging liquid after filling. The mechanical structure should be drawn with CAD drawing software and then machined as per the drawing. The system adopted Delta DVP 48EH PLC to control cylinder and stepping motor to drive the fixed plates of locating cone and needle tubing for filling, so as to achieve the precise positioning of the blood type card by locating cone and the accurate control of descending stroke of needle tubing for filling in blood type card. Meanwhile, the quantitative liquid was injected into the blood type card combined with XMP6000 micro-pump. In the actual production, the phenomenon of generation of air bubbles and wall-hanging liquid after filling was greatly improved. The system has reached the technological requirements in the process of operation, and it is easy to operate, stable, reliable, safe and of high automation, which is applicable to the production for small-/medium-sized enterprises.