Liu opened her season with a silver medal at the 2017 Asian Open Trophy, where she finished second to Japan's Mana Kawabe. She was the youngest skater to compete in the junior division at the 2018 U.S. Championships in San Jose, California. She won the competition, despite suffering from a cold and sore throat. She scored a season's best in the short program with an almost seven-point lead going into the free skate. Her short program included three level-4 spins, a triple flip-triple toe loop combination, and a triple Lutz, earning her 63.83 points. She earned 120.33 points during her long program, after landing two double Axels and seven triple jumps, which were all backloaded in the second half of the program. Liu was given extra points on all her jumps, except for the triple flip-single loop-triple Salchow combination. She earned an overall score of 184.16 points, almost 18 more than silver medalist Pooja Kalyan and the second highest-ever score on the junior level. Despite winning the gold, Liu was ineligible to compete at the 2018 World Junior Championships because she was not old enough. She was sent to the 2018 International Challenge Cup instead, where she won the advanced novice silver medal behind Hanna Yoshida of Japan.