 He was the seventh son of his pirate father Zheng Lianfu (鄭連福) and his wife Lin Xiu (林秀), hence the nickname Zheng Qi.Zheng Qi was recruited by Tay Son dynasty in 1788, and later became one of the most important subordinates under Chen Tianbao.From 1788 to 1799, Zheng frequently attacked southern coast of Qing China together with Mo Guanfu, Liang Wengeng (梁文庚) and Fan Wencai (樊文才).