This thesis aims to examine and analyze the concept of social work as a reform of criminal punishment in Indonesia in the National Criminal Code and to examine and analyze the suitability of social work to the principles of proportionality and justice in sentencing. This research is a normative research using a legislative and conceptual approach. The legal material collection technique uses literature studies and legal material analysis uses systematic legal interpretation by interpreting laws. The results of this study are that social work is conceptualized as an alternative to short-term imprisonment and light fines by considering various aspects such as confession, ability, consent, and the social history of the defendant. Social work is in accordance with the principles of proportionality and justice in sentencing because it provides sanctions that are commensurate with the level of error. Social work not only emphasizes retribution, but also encourages recovery and improvement through positive contributions to society. However, social work still requires more detailed and comprehensive implementing regulations so that social work can be implemented consistently and effectively by law enforcement officials.