The invention relates to a sampling unit for the concentrates preparation device. The unit comprises a base body, a movable rod, a limiting pin, a sampling chamber, a sampling bore, an axle sleeve and an isobaric chamber. The sampling chamber passes through the upper and lower surfaces of the base body, the isobaric chamber is a cylindrical blind bore, the isobaric chamber passes through the front surface of the base body and passes through the front and back surfaces of the sampling chamber. The axle sleeve has an interference fitting with the isobaric chamber, the movable rod hermetically slidingly mates with the axle sleeve, the head and tail ends of the gas permeable passage respectively communicate with the isobaric chamber and the outside. Concentrates can be taken out through the sampling bore of the sampling unit, the movable rod can take samples freely with the help of gas permeable passage for keeping the pressure balance of ends of the movable rod.