Abstract: Aiming at the circumstance that the refined copper is fracture in drawing bench process,the refined copper is carried on observing the microstructure and analyzing its composition by the electronics probe analysis instrument. The results indicate that the refined copper existences some Sn element,which accumulate and come into being black particle impurity,and which make the grain boundary of copper become more bulky obviously. The formation reason of those problems is discussed,and the resolved method is put forward.