Introduction: Preschool children with autism spectrum disorder and their parents face many difficulties in daily lives, including children's adaptive functioning, parenting skills, and parenting stress. Therefore, effective and economical interventions are very important to support them. With appropriate theoretical bases, a parent-training program could be effective, economical, and feasible while the clinical manpower is insufficient. Among current intervention programs, the play concept and the developmental, individual difference, and relationship-based (DIR) model match the philosophy of occupational therapy. Previous research had showed the play- and DIR-based parent-training programs would improve children's communicative development. However, the empirical evidence was still weak due to poor research designs and little research was comprehensively investigated children's adaptive functioning. Moreover, the results of improvement in parenting skills and reduction of parenting stress were not consistent. Aim: This study would implement a dose-matched control group and comprehensive measurements to examine if the play- and DIR-based parent-training program would improve children's adaptive functioning and parents' parenting skills as well as reduce parenting stress. Hypotheses: We hypothesized that the better improvements would show in the parent-training program than those in the traditional program. Method: We recruited 40 preschool children with autism spectrum disorder and their parents and randomly assigned them to either the parent-training program group or the traditional program group after pretest phase. Both of them conducted 14-week intervention programs and were assessed after interventions. Children's development levels and adaptive functioning were assessed by the Functional Emotional Assessment Scale (FEAS), the Chinese version of Psychoeducational Profile-third edition (CPEP-3), and the Vineland Adaptive Behavior Scales (VABS). In addition, parents' parenting skills were assessed by the FEAS and parenting stress was evaluated by the Parenting Stress Index-Short Form.