Joined the group member Jin Yushuo on May 3, 2019 as a trainee to participate in the reality program “PRODUCE X 101”. On March 15th, as a class A trainee, the theme song evaluation film will be released. In the positioning evaluation, he performed in the Rap X Dance category “Tortoise Ship”, with 680 votes at the scene, becoming the first place in the X category. Gao Yan’s figure and excellent rap performance made the ranking rise steadily, from 38 spots in the first episode to second place in the second ranking ceremony. In the third week of June, the performers ranked second. In the final return, Lee Hyun Hyuk got the eleventh place, but because of the new format of the show, the last debutant (X) was calculated based on accumulated votes instead of the top 11 debuts, and was not eligible to become an X1 member.