In order to implement juvenile protection, to perfect the development both physically and mentally and to avoid law infringement resulting as an adult repeat offender in the future, the government strives to combine all efforts of judicial, police administration, legal affairs, education, politics, society and private groups in hoping that an effective prevention can be achieved. What are the main factors that result a juvenile delinquency? How a policy can be improved? It is found that it is necessary to emphasize on ”statistical data file establishment”, ”establishment of crime forecast model” and ”measurement tool” so that it can be on time to respond to the changing circumstances in juvenile delinquency. The theory of localized crime commitment should be implemented so as to prevent and reduce crimes under different crime commitment conditions and crime commitment models.