We have developed a single crystal copper bonding wire to carry out ball bonding testing,and bonding rally（BPT）and shearing stress（BST）were measured to the welding joint on ball bonding wire,meanwhile,the microstructure,interface morphology and micro-hardness of the bonding point were investigated.The results show that BPT and BST of the welded point in ball bonded wire exhibits approximately normal distribution,showing a higher credibility.The CPK（process capability index）of the single crystal bonding wire with 50 μm in diameter makes 1.8 or more than 1.8,exhibiting desirable parameters.The interface of the welded point after reliability testing exhibits clear and relatively straight,in which absence of trace dispersively distributed intermetallics in the interface and the Kirkendall cavity can be observed,showing stable electron properties and interface structure.