Cao Yang began his career graduating through the Tianjin Teda youth system eventually joining the senior team when he made his league debut on September 17, 2000 against Yunnan Hongta F.C.
[2] A versatile defender with good offensive and defensive ability who could also play in midfield as well as being physically tall, saw Cao firmly establish himself within as a permanent fixture within the Tianjin team by the end of the 2002 league season.
During their debut appearance in the AFC Champions League Cao Yang had the honor to be named as their captain against Kawasaki Frontale.
His performance in the tournament was considered good enough for him to be promoted to the senior team by the Chinese caretaker coach Shen Xiangfu on December 7, 2002 in a friendly game against Syria in a 3–1 victory.
[4] With Zhu Guanghu as the national teams coach Cao's international career would start to see him become a regular within the team and he was included in the squad that won the 2005 East Asian Football Championship as well as also being in the squad that took part in the 2007 AFC Asian Cup.