O
- (Xilin Gol Meng) Ondor Sum
- (Hulunbuir Region) Oufu
- (Hohhot Shi) Ou’liangmao
- (Alxa Meng) Onotin Sair
- (Xilin Gol Meng) Olan Hudagin Sum
- (Hinggan Meng) Obor Jalag
- (Tongliao Shi) Olji Moron
- (Bayannur Shi) Oljit
- (Tongliao Shi) Ondor Had
- (Alxa Meng) Ondor Mod
- (Ordos Shi) Ordon Nur
- (Bayannur Shi) Onggon
- (Bayannur Shi) Onggon Tegin Sum
- (Xilin Gol Meng) Onggon Ul Sum
- (Alxa Meng) Ongt Gol
- (Hulunbuir Region) Onor
- (Tongliao Shi) Orbog
- (Xilin Gol Meng) Orgon Tal Sum
- (Hulunbuir Region) Orqohan
- (Tongliao Shi) Ouli
- (Ordos Shi) Obon Xil
- (Ordos Shi) Ordos