After the Song dynasty replaced Later Zhou in 960, Cao participated in the conquest of the Later Shu state in 965, where he distinguished himself from the other generals for disciplining his troops from pillaging the area, and was promoted as a result.

In 974, he was named the overall commander to invade the Southern Tang state, which he successfully conquered in 976, again taking careful measures to prevent unnecessary killing.

Before the age of 20, Cao Bin served under his father as a minor general, and Wu Xingde (武行德), the military governor of Chengde Commandery, was reportedly very impressed by him.

At that time his maternal aunt Lady Zhang (張氏) was married to Guo Wei, another military governor.

Once, a messenger refused to believe he was the general, saying "how could the emperor's relative dress in modest clothing and sleep on a commoner's bed?"