In 2006, when he was discharged from the military, he joined the Doosan Bears as a trainee. At that time, he tried to practice and develop his skill. At last, The Doosan's Head coach Kim Kyung-Moon selected him and Lee tried to survive, not to lose the opportunity. As a result, he could settle down the major group of Bears.
His biggest advantage was to run fast. Therefore, he made fifty-one steals in that season even though his team failed to join the post-season in 2006. Next year, he made forty-seven steals while he hit a homer and made a 0.316 hitting average. He can run to the third base if he hit a ball to the further course of a stadium. He can steal to the second or third base in any situation even a good pitcher marks tightly or a catcher throws a ball exactly. In addition, he can catch a flying ball which drops into the point in which any outfielder get hardly or miss.
He contributed and led the Bears to the Final round of 2007 and 2008 post-season. Especially he made 0.517 hitting average and three SBs in playoffs 2008. And won the Most Valuable Player straight two years in 2007 and 2008 playoff of two post-seasons.