Xu says he earns more than 500 yuan a day crooning on the subway, which is much more than he can get singing in the tunnels.
He recalls he was too shy to sing when he first started in 2009. So, he followed a friend, who was also a subway singer, and accompanied him with his guitar.
He had been approached by some record companies but isn't interested in being tied to any of them.
I don't want to have to compromise with the record companies, he says.
In March 2012, he also got a phone call from the producer of The Voice of China, Zhejiang Satellite TV Station's popular singing contest.
The producer praised Xu's vocals but wanted him to sing pop songs, which doesn't appeal to Xu.
I want to sing my own songs, he says.
Although he turned down such opportunities, which could improve his living condition, Xu feels he's fulfilling his dreams albeit slowly.
Xu recently formed a band called Bullet Cover with drummer Cao Xingle, bassist Zhang Hao and keyboardist Cao Dawei. The group plans to release their debut album, The Voice in the Corner, in 2013.