A double-weighing metering stock bin, comprising a belt conveying mechanism, a stock bin body, a wide range weighing mechanism and a small range weighing mechanism, wherein the stock bin body is erected on the belt conveying mechanism, a feed inlet is formed at a position in the top of the stock bin body close to the back end along the conveying direction of the belt conveying mechanism, and a discharge port is formed at a position in the bottom of the stock bin body close to the front end along the conveying direction of the belt conveying mechanism; the wide range weighing mechanism is mounted in the belt conveying mechanism and is close to a position of the feed inlet of the stock bin body perpendicularly projected on the belt conveying mechanism; the small range weighing mechanism is mounted in the belt conveying mechanism and is located behind the discharge port of the stock bin body; the belt conveying mechanism comprises a frame, a driving roll, a driven roll, a belt and a driving device; the driving roll shaft is arranged at the back end of the frame as a shaft, the driven roll shaft is arranged at the front end of the frame as a shaft, the belt encircles the driving roll and the driven roll, and the driving device is mounted on the frame and drives the driving roll to rotate, wherein the stock bin body is supported on the frame of the belt conveying mechanism by means of a stock bin rack; a material throwing device below the feed inlet in the stock bin body is arranged between the wide range weighing mechanism and the small range weighing mechanism; the material throwing device comprises a material throwing roll bracket, a plurality of material throwing rolls (242a, 242b, 242c, 242d) and a driving motor which drives the plurality of material throwing rolls (242a, 242b, 242c, 242d) to rotate; the material throwing roll bracket is obliquely arranged on the stock bin rack in a way that the back end of the material throwing roll bracket is higher than the front end thereof; the plurality of material throwing rolls (242a, 242b, 242c, 242d) are parallelly arranged on the material throwing roll bracket as shafts, and the driving motor is mounted on the frame and is in driving connection to each of the material throwing rolls (242a, 242b, 242c, 242d) and wherein the back end of the material throwing roll bracket is hinged to the stock bin rack while the front end thereof is mounted on the stock bin rack through a lifting adjustor; the lifting adjustor comprises a left adjusting vertical plate, a right adjusting vertical plate, an adjusting transverse plate, an adjusting mandrel, an adjusting screw and an upper adjusting bolt and a lower adjusting bolt; the left adjusting vertical plate and the right adjusting vertical plate are vertically arranged on the left side and the right side of the stock bin rack and are lower than the back end of the material throwing roll bracket; inclined holes (510aa, 510ba) are symmetrically formed in the left adjusting vertical plate and the right adjusting vertical plate; the adjusting mandrel is arranged at the front end of the material throwing roll bracket and two ends of the adjusting mandrel are placed in the inclined holes (510aa, 510ba) of the left adjusting vertical plate and the right adjusting vertical plate; the adjusting transverse plate is arranged on the stock bin rack and is located above the left adjusting vertical plate and the right adjusting vertical plate; the adjusting screw vertically penetrates through the adjusting transverse plate and is fixedly connected to the adjusting mandrel; and the upper adjusting bolt and the lower adjusting bolt are arranged on the adjusting screw in a screwing manner, respectively, and are located above and below the adjusting transverse plate.