SING's predebut team was 14 members. Six of them ended up debuting (incluiding Chen Li, who debuted later) and three of them participated on some single as trainee.

• Lai Meiyun. (on hiatus; debut team)
• Chen Li (current member; debuted on 2016)
• Lin Jinyi (debut team)
• Gong Tianying (debut team)
• Cai Sha (debut team)
• Bian Li (current member; debut team)
• Chen Wenrou (keep as trainee; participated on some singles)
• Wang Wenjie (keep as trainee; participated on some singles)
• Zhou Yanjun (keep as trainee; participated on some singles)
• Yian Qingyuan
• Qiao Man
• Xu Hailing
• Li Yina
• Qi Guojuan (left early)