In recent years, the Chip-on-Board (COB) package technology has become popular in semiconductor industries. The COB technology, in which the dies are directly mounted onto a printed circuit board (PCB) with bonding wires connecting the die and leads. Besides solder bumps, wire bonding is still the most popular interconnect method. With the development of wire bonding technology in the COB package, we can realize advanced processes with good performance by new wire bonding equipment and more powerful software. However, there are still many challenges to be overcome in the bonding process. In this paper, we did experiments to optimize the bonding parameter using 1.0mil Au wire on COB and successfully found the optimal range of bonding parameters through DOE (Design Of Experiment). By the optimal solution, we further improved the bondability; the second bonding quality was also improved by using BSOB (Bond Stitch On Ball) bonding.