Lee reached at Youth- events a lot of international successen. At the Youth- asian championships he became champion with the team and 2008 he won the singles category. Also Lee took at Youth- world championships three silver namely 2007 and 2008 in the team competition and 2008 in the doubles with Seo Hyun-deok. His first medals at the World Tour-Gold in the singles and bronze in the doubles- he won at the Slovenia Open 2010, in that Lee came to the top 100 in the world rankings. In the doubles he became the bronze medal at the World Tour Grand Finals, with Seo Hyun-deok again. After the Korea Open 2011, where Lee won silver, he became with place 22 a new record. This position he improved first after four years.