Despite both plane toilets being free at the time, the woman decided it was more spacious in the aisle.
Along with a friend, the mum held the child while she used the staff sit-down area as a toilet.
A few days earlier a family let their child use the seat as a toilet on the same airline as the plane was landing and the loos were closed
A snap of the incident shared on Chinese social network Weibo on Sunday has gone viral, with shocked users questioning the mum's parenting skills.
According to The Shanghai Morning Post, the woman was unapologetic to plane staff, claiming the toilets were 'too narrow for three people'.
The trio were travelling on an internal flight on Shenzhen Airlines from eastern China to southern China.