Zou Shiming competed in his first amateur boxing competition at the 2004 Asian Amateur Boxing Championships and won silver, losing in the final to Noman Karim but qualifying for the 2004 Summer Olympics. At the 2004 Summer Olympics, he won his first match by beating Rau'shee Warren in the round of 32. He lost to eventual champion Yan Bartelemí in the semi-finals and ended up winning bronze. Zou won the 2005 World Amateur Boxing Championships by beating Pál Bedák in the final, becoming the first ever Chinese boxer to win the tournament. At the 2006 Asian Games, Zou won gold by beating Suban Pannon 21-1 in the final match. He repeated his triumph from 2005 at the 2007 World Amateur Boxing Championships, beating David Ayrapetyan early in the tournament and Harry Tanamor in the final; however, Zou had to settle for silver at the 2007 Asian Amateur Boxing Championships, losing in the final against Pürevdorjiin Serdamba.