Su had overseen the development of China's banking payments system for many years before he retired from the People's Bank of China last month.
Su would replace Liu Tinghuan, the current China UnionPay chairman, Sina.com said, citing unnamed sources.
Fast-expanding China UnionPay is set to face growing tensions as it competes for global market share with rivals such as Visa, MasterCard Inc and American Express Co.
These foreign companies are aggrieved that UnionPay has a monopoly on processing credit-card and debit-card transactions in China.