The invention discloses a fully-automatic plastic batching device. The device comprises a weight reducing scale batching area in which a plurality of storing bins are arranged, wherein a weight reducing scale is mounted at a discharging port in the bottom part of each storing bin; a transversely-penetrated chain double-rail conveying line for conveying a movable hopper is arranged at the bottom part of the weight reducing scales; a two-way moving hoisting rail is arranged at one side of the outlet end of the chain double-rack conveying line; a lifting assembly is mounted on the two-way moving hoisting rail; the movable hoppers are driven by the two-way moving hoisting rail to move to a three-dimensional mixer; each movable hopper is clamped by the three-dimensional mixer through an oil cylinder, and a motor rotates to mix raw materials in the movable hopper; after the raw materials are mixed, each movable hopper moves to a material picking device through the two-way moving hoisting rail; an AGV trolley is arranged at the material picking device and used for carrying each movable hopper to a production line.