Abstract: Objective To explore the relationship between juvenile delinquents' lifestyle and their family environment and to provide reference for preventing juvenile delinquence.Methods Totally 302 juvenile delinquents chosen from Shanxi Juvenile Prison and 296 middle school boy students(from junior two to senior grade one)chosen with stratified sampling from two middle schools in the urban and rural of Xi'an city were investigated with a physical and mental health questionnaire and the Family Environment Scale.Results The juvenile delinquents' scores of social contact,family conflict,and active recreation were 8.84±2.02,4.53±1.92,and 4.94±1.58,higher than those of the middle school students(8.01±2.44,3.72±2.04,and 4.16±2.04)(all P=0.000).The juvenile delinquents' scores of diet,medicine,exercise,leisure,family cohesion,intellectual culture orientation,and control were 6.77±2.21,6.94±2.86,6.17±2.38,6.09±2.13,5.18±1.96,2.81±1.43,and 2.91±1.53,respectively,which were lower than those of the middle school students(8.83±2.14,10.88±2.23,8.36±2.19,7.95±2.23,5.95±2.31,3.47±1.97,and 3.97±2.09)(all P=0.000).The delinquents' lifestyle was correlated with their family environment in several dimensions(r=-0.208-0.374).The family cohesion,intellectual culture orientation,organization,and control were positive predictors of lifestyle(β'=0.116-0.253,P=0.000-0.005);family conflict and active recreation were negative predictors of drug use(β'=-0.126,P=0.002;β'=-0.272,P=0.000).Conclusion The juvenile delinquents' lifestyle is unhealthy and their family environment is worse than that of middle school students.The family environment has obvious influence on juvenile delinquents' lifestyle.