The woman got into an argument with a group of young men on the train in Changsha in Hunan province who had complained about the noise her two-year-old child was making, local media reported.
One of the men pushed her sister as they were getting off.
She then got back on, demanding an apology, and stopped the train by blocking the door with her body and putting one foot on the platform, the report said.
Police were called and six other trains were also delayed during the dispute on Tuesday.
She said she was acting in self defence and did not violate any laws or regulations.
