Abstract: The metallurgical production flowsheet of copper-clad steel 6A (/% : 0.03 ~ 0.06C, 0.02 ~ 0.05Si, 0.15 ~0. 25Mn, ≤0.015P, ≤ 0.015S, 0.02 ~0.05Al) is hot metal desulphurization- 120 t BOF-LF-140 mm x 140 mm billet casting-continuous rolling to Φ6.5 mm coil- annealing. The breaking wire of copper-clad steel 6A during cold-drawing process from Φ6.5 mm cold-drawing to Φ0.45 mm wire has been analyzed by scanning electron microscope. Results show that there are coarse spheroidized cementite clusters at center line near the fracture of Φ0. 45 mm wire. During cold-drawing process due to the hardness of pearlite higher than that of ferrite, the fine cavities initiate at tip of pearlite and with increasing drawing passes the cavities evolve as transverse ℃- shape cracks finally led to wire breaking. With decreasing carbon and manganese content in steel respectively from 0. 05% and 0.23% to 0.03% and 0.17% , decreasing overheating extent of liquid in tundish from 35 ℃ to 25 ℃ and optimizing electromagnetic stirring parameters from 250M, 1. 2 Hz to 400 A, 1. 2 Hz, the phenomenon of pearlite clusters at coil center is improved and the cold-drawing wire broking ratio decreases from 1. 0 times per ton steel to 0. 2 times per ton steel.