Loss-in-weight feeder system is used for the compounds of polymer materials and auxiliary formulations by medium and small parallel co-rotating twin-screw extruder in laboratory. The system is composed of several small-flow loss in weight feeder. The range of the weighing sensors and the type of feeding screws in the weight sensor scales can be combined according to the actual needs of the feeding, to achieve high-precision flow control of different types of materials and a variety of flow ranges, and the flow of all weight loss scales can be adjusted in tandem to achieve real-time setting of the mixing ratio of different compounds of the material formula.