A 15-year-old child who steals a mobile phone can generally be disciplined by the public security. Because the 15-year-old child who steals a mobile phone does not bear criminal responsibility because he does not reach the age of criminal responsibility, the public security organ cannot investigate criminal responsibility, but should order his parents or guardians to discipline him; When necessary, they may also be taken in by the government for reeducation. The age of criminal responsibility refers to the age at which the perpetrator must be held criminally responsible for his own criminal acts according to the law.
 Legal basis
 Article 17 of the Criminal Law [Age of criminal responsibility] A person who has reached the age of 16 and commits a crime shall bear criminal responsibility.
 If a person who has reached the age of 14 but not the age of 16 commits intentional homicide, intentional injury that causes serious injury or death to another person, rape, robbery, drug trafficking, arson, explosion, or the dropping of dangerous substances, he shall bear criminal responsibility.
 If a person who has reached the age of 12 but not the age of 14 commits the crime of intentional homicide or intentional injury, causing death to another person or serious injury to another person by special cruel means, resulting in serious disability, and the circumstances are flagrant, and the Supreme People's Procuratorate approves the prosecution, he shall bear criminal responsibility.
 Persons under the age of 18 who have been investigated for criminal responsibility in accordance with the provisions of the preceding three paragraphs shall be given a lighter or mitigated punishment.
 If he does not receive criminal punishment because he has not reached the age of 16, his parents or other guardians shall be ordered to discipline him; When necessary, special corrective education shall be carried out according to law.