By cross-sectional study and means of questionnaire, the current research study correlates parental monitoring with juvenile drug use among youths in a juvenile detention center in China. Previous research regarded parental monitoring as a single dimension and neglected the two patterns of drug use (juvenile drug use and the kinds of drug use). To fill in this gap, this study captures two dimensions of parental monitoring, parental expectations for children and parental knowledge about children, and also analyzes the two patterns of drug use. In this study, data was collected by an anonymous, voluntary and self-administrated method. According to the results of the analyses, when parents set rules for children, the youths are less likely to use drugs; however, parental expectations have no correlates with the kinds of drug use for the adolescents who have used drugs. Compared with setting rules, the results reveal that merely parental knowledge about youths’ whereabouts, associations and activities has no correlates with the two patterns of juvenile drug use. The results can have policy implications and help more youths stay away from drugs.