Methods: In this semi-experimental study with pretest and posttest design by control group, Parent-Child Relationship Scale (PCRS) was determined in 40 random clustering selected mothers of children with ID before and after the intervention. The aim of the scale was to obtain information with regard to emotional aspects such as conflict, closeness, dependency, and positive relationship. The mothers were randomly assigned in experimental and control group with equal numbers. Experimental group participated in 8 sessions (each session lasts for 60 minutes twice a week) and were trained by Triple-P, but control group did not. Multivariate analysis of covariance (MANCOVA) was used for analyzing the data by using SPSS software (version 16, SPSS Inc., Chicago, IL). 

Results: There were significant differences between experimental and control group with respect to emotional aspects such as conflict, closeness, dependency, and positive relationship as a whole after participation in intervention sessions (P<0.001). 

Conclusion: There was a significant decrease in conflict and increase in closeness, dependency, and positive relationship in experimental group. Our findings showed that group Triple-P has led to promotion of relationships of mother-child with ID.