Preschool teachers face challenges when working with children with autism spectrum disorder (ASD). Currently, there are extensive studies on preschool based early interventions (EIs), but there are limited studies conducted to examine the challenges faced by preschool teachers when implementing EI with children with ASD. There is no available study in this regard in Sri Lanka. Thus, this study aimed to investigate the preschool teachers’ challenges associated with preschool based EIs for children with ASD and the strategies preschool teachers use to overcome these challenges in Sri Lanka. A qualitative approach was employed, and four Sri Lankan preschool teachers were interviewed. Thematic analysis was done, and four major themes were identified: institutional challenges, challenges to professionalism, parental challenges, and inclusive practices for identified challenges. This study discussed the preschool teachers’ challenges in implementing these interventions at different levels in Bronfenbrenner's bio ecological model and the adaptive strategies they utilized to overcome these challenges in relation to their intrinsic motivation as in Self determination Theory(SDT). Future studies were highlighted including the need for evaluating the effectiveness of adapted strategies.