The materials of this study were based on 60 individual studies from January 2000 to December 2011. The effect size is correlation, and the analysis is based on random effects model because of heterogeneity of outcomes. The main findings are as follows: First, we categorized two main variables: protective and risk variables. Second, for the protective variable, individual, family, school, society & culture factors were in order. The overall effect of protective variable is -.281. Third, for the risk variables, individual, family, school, society & culture factors were in order. The overall effect of protective variable is +.339. Fourth, sub-group analysis was conducted and reported the results such as gender, instrument and so on. These findings showed that protective and risk variables were related to depression of middle school students. The psychological intervention and counseling might be effective to decrease the depression among middle school students. The implication and limitation of analysis results and the direction of future research were discussed.