One of Autism Spectrum Disorder (ASD)' major characteristics is the lack of social communication and interaction with other people. Recently, some research studies have examined robot-based interventions for children with ASD. In line with those studies, the present paper introduces our ongoing research on robot-mediated imitation training for children with ASD. In this paper, we focus on designing human-robot interaction for autism intervention whereas previous studies largely focused on developing robots for intervention. Several human-robot interaction scenarios for robot-mediated imitation training were developed with emphasis on facilitating communication between a child and a therapist. Two main concepts (triadic interaction and reciprocal imitation training) were adopted and modified to increase the efficacy of the intervention. The developed interaction scenarios described how a robot can be integrated into the clinical sessions and the requirements for a robot. The field trials for examining the efficacy of robot-mediated imitation training will be carried out.