The invention discloses a numerical-control band sawing machine for a flat head of a metal packing case. The numerical-control band sawing machine comprises a lathe bed, a guide rail, a band saw blade and a rack, wherein the guide rail and the rack are separately horizontally fixed onto the lathe bed; the band saw blade winds on two rotary wheels, one rotary wheel is driven by a band saw drive motor to rotate as a drive wheel; the two rotary wheels are arranged in a spaced mode and are mounted on a supporting frame; two vertical rods of the supporting frame are separately matched with one guide rail for realizing longitudinal sliding; a vertical rod close to the rack is connected with the gear through a connecting rod; the gear is engaged with the rack, and is driven by a longitudinal motion servo motor to longitudinally move along the rack; the longitudinal motion servo motor is connected with a motor driver; and the motor driver is connected with a numerical control device. The numerical-control band sawing machine disclosed by the invention can meet the requirements of processing flat heads of large-dimension metal packing cases, the processed surfaces are free of ablation and oxidization, and the whole processing process is precisely controlled in a numerical-control mode and is completed through one saw-cutting, so that production efficiency is high.