His only real success came in the 2019 IBSF World Under-18 Snooker Championship, where he reached the final, losing 5–2 to the 13-year old Jiang Jun.

Originally Gao's coach Ju Reti had qualified, but gave up his place in order to allow his pupil to gain experience.

He beat heralded juniors Ben Mertens, Dean Young and Wu Yize, before overcoming Sean Maddocks 5–2 in the final.

In subsequent tournaments Gao had wins against Zhao Jianbo, Kacper Filipiak, Mitchell Mann and Duane Jones.

In the World Championship, Gao beat experienced player Paul Davison 6-3 and played very well against Lyu Haotian to lead 5–3.