Laogai (Chinese: 劳改), short for laodong gaizao (劳动改造), which means reform through labor, is a criminal justice system involving the use of penal labor and prison farms in the People's Republic of China (PRC). Láogǎi is different from láojiào, or re-education through labor, which was the abolished administrative detention system for people who were not criminals but had committed minor offenses, and was intended to "reform offenders into law-abiding citizens". Persons who were detained in the laojiao were detained in facilities that were separate from those which comprised the general prison system of the laogai. Both systems, however, were based on penal labor.

In 1994 the laogai camps were renamed "prisons". However, Chinese criminal law still stipulates that prisoners able to work shall "accept education and reform through labor". The existence of an extensive network of forced-labor camps producing consumer goods for export to Europe and the United States became classified. Publication of information about China's prison system by Al Jazeera English resulted in its expulsion from China on May 7, 2012.

The system has been estimated to have caused tens of millions of deaths and it has also been likened to slavery.