Cao Zheng was born into a family of butchers in Kaifengfu and was once learnt martial arts from Lin Chong. He was an excellent butcher and earned himself the nickname 'Demon carver' (操刀鬼). Once, Cao Zheng went to Shandong on a business trip. Unfortunately, he got himself into debt and owed the landlord a large sum of money and could not return home. He opened a rented restaurant to earn himself some money to repay the debt.
Once, Yang Zhi was put in charge of escorting the convoy of birthday gifts, but he was drugged and the gifts were robbed by Chao Gai and his friends. He felt very unhappy and went to Cao Zheng's restaurant for a meal without paying, and had a fight with Cao. Cao used a pole to hit Yang Zhi but he still lost to Yang Zhi, and he admitted defeat, becoming friends with Yang.