The invention discloses a molding powder pulverizing device. The molding powder pulverizing device comprises a case, a first pulverizing chamber, a hobbing cutter, a movable cutter head, a fixed cutter head, a sieve plate, a motor and a second pulverizing chamber, wherein the first pulverizing chamber is arranged above the case; a feeding hopper is arranged on the first pulverizing chamber; the hobbing cutter is mounted in the first pulverizing chamber and is driven to rotate by an auxiliary motor; the second pulverizing chamber is arranged in the case; the movable cutter head is arranged in the second pulverizing chamber, and is driven to rotate by the motor; the fixed cutter head is arranged above the movable cutter head; a discharge groove is formed in the fixed cutter head and communicates with a discharge opening; the sieve plate is arranged under the movable cutter head; a plurality of sieve holes are formed in the sieve plate; and a collecting box is further arranged at the lower part of the case. Materials can be pulverized thoroughly in a graded manner, the production efficiency is improved, molding powder particles with relatively consistent sizes are obtained, and the quality of powder coating is guaranteed.