The purpose of this research is to examine the legal responsibilities in the criminalization of children's sexual crimes in cyberspace in Iran's legal system. This study describe the current state of existing laws and regulations against children's sexual crimes by examining the criminalization. The results of the research show that the governments should criminalize child pornography, whether in pictorial or non-pictorial form, or by suggesting, facilitating, arranging and encouraging. Despite this, unfortunately, there is still a considerable gap in the internal laws of the countries with new forms of harassment and abuse and online sexual exploitation of children. The governments should pay serious attention to the extent that people's actions in uploading or downloading cases of harassment and abuse are available. this research shows that in the laws of the Islamic Republic of Iran there are no appropriate penal laws to prevent all instances of abuse of children in cyberspace. Although in the Child and Adolescent Protection Bill, to some extent It has been discussed this issue and regarding the precise separation of issues and determining the punishment for each act based on the importance of the crime, the legal weakness in protecting the victimization of children in cyber space is evident. Therefore, it is the duty of the legal and regulatory institutions to considered sexual crimes against children by recognizing the different dimensions and layers of injury as well as the international definitions and experiences of other legal systems. By criminalizing the various dimensions of this phenomenon, the legitimacy and necessity of spending the actions against children should considered and they should attempt for prevention of these crimes by enlightening families as well as child support groups.