Introduction: Parents are the first ones to interact with child during the most critical growth years. They play a key role in child's psychosocial development. This article aimed to study the effect of mother training using Barkley's Method on parent-child relation improvement of 1st, 2nd, and 3rd grade elementary students diagnosed with ADHD of Shahre Kord, Iran. Methods: This is an experimental study with pretest, posttest, and control groups. The statistical population consisted of all female and male, 1st, 2nd, and 3rd grade elementary students diagnosed with ADHD in the academic year 1394-95. A total of 38 students were enrolled as the sample using random sampling. They were split in two groups (Experiment (19) and Control (19)). Prior to the intervention, both groups completed the Parent-Child Questionnaire as the pretest. Then, the experiment group underwent a total of ten 90-minute parent training sessions. Control group did not receive any training. The data were collected using Vanderbilt ADHD Diagnostic Scale, Parent-Child Relations Questionnaire (PCR), and Clinical Interviews. To analyze the data, the SPSS software, version 23 and MANOVA was used. Results: According to the findings and previous studies, it is concluded that intervention was effective in parent-child relations of students diagnosed with ADHD. This study helps to psychologists, counselors, psychiatrists, and families in achieving and understanding modification techniques and safe therapy to improve parent-child relationship.