Externalizing behaviour disorders in childhood, cause many psychological problems for parents. Oppositional defiant disorder one of the childhood disorders that cause psychological problems in the parent's and management of children's behavior creates problems, to the so purpose of the current study was to investigate the effect of behavior parent training methods to mothers of children with oppositional defiant disorder on reducing depression these mothers. The research method was quasi-experimental with pre-test and post-test design and control group. To do so, 30 mothers of children with oppositional defiant disorder were selected using at-hand sampling and divided into control and experimental groups. Both groups filled out CSI-4 scale and beck inventory depression. In the next step, the experimental group was instructed behavior parent training in 9 ninety-minute sessions while the mothers in control group went on their normal procedures. At the end of the instructional session, both groups filled out the mentioned questioners as the post-test. Covariance analysis was used for analyzing data. The results of the analysis of covariance showed that instructing behavior modification methods improved depression scores in mothers (P<0/05) in comparison with the control group. The results totally showed that behavioral training to mothers improves their psychological disturbance in mothers with behavioral disorders.