The boy reportedly filmed the murder and sent the clip to friends via popular messaging app WeChat. He was arrested several days later after a friend showed the clip to his mother.
The incident took place in the town of Wenxing in Sichuan province.
Local police confirmed the case with the BBC but gave no further details, saying it was still being investigated.
The boy killed his mother after a quarrel on Sunday night, reported Radio Free Asia, citing local sources.
He then decapitated her and stored her head in a bucket, before disposing of it in a drain outside their home, according to the news outlet.
It also said the murder was not discovered until Wednesday, when one of the boy's classmates showed the video clip to a parent who immediately reported it to the police.
The boy was said to have been arrested at school.