Suen Yin Liu or better known as S.Y. Liu was a student of. Very little is known about him, as he retired from active teaching and retained a quiet life. Some accounts suggest he first learned from . While accounts from his students suggest he only learned from Cho On.
According to, a student of S.Y. Liu and author in his own write, Liu was a restless youth, that was driven to practise Kung Fu. He frequently tested his Wing Chun Kuen skills against other arts and taught on behalf of Cho On. Liu ended up having to work for financial reasons, and ended up retiring from active teaching.
He was known to have favored theform, due to its combat effective nature.