This study sought to promote the safety of citizens by seeking ways to utilize private security during the multi-cloud execution event. On October 29th, a disaster occurred in Itaewon. In order to prevent the recurrence of such a disaster, the domestic security environment was illuminated, and it was confirmed that large and small changes such as office reorganization according to the self-governing police system, reduction and abolition of riot police, and changes in security demand in the metropolitan area generally resulted in changes in manpower. In order to propose private-police cooperation as a countermeasure, we investigated cases of cooperation in public security overseas and tried to link the results with the domestic security situation. The situation of public security cooperation in France, Japan, Germany, the United States, and Australia was explored, focusing on themes such as multi-group events, private security, and security assistants. Based on the review results, it was proposed to expand the operation of public security assistants, establish a new provision for congestion guard work, check event safety management guidelines, and establish a communication system for public-private cooperation.