Introduction The aims of this study are to (1) conduct a systematic review of the intervention literature in preschool children with autism spectrum disorder (ASD), including types of interventions that are tested and the classification of outcome measures used and (2) to undertake a meta-analysis of the studies, allowing for the first time the comparison of different approaches to intervention using comparative outcomes. There are a number of alternative modalities of intervention for preschool children with ASD in use with different theoretical background and orientation, each of which tend to use different trial designs and outcome measures. There is at this time an urgent need for comprehensive systematic review and meta-analyses of intervention studies for preschool children with ASD, covering studies of adequate quality across different intervention types and measurement methods, with a view to identifying the best current evidence for preschool interventions in the disorder.

Methods and analysis The authors will perform a systematic review of randomised controlled trials for preschool children with ASD aged 0–6 years, along with a meta-analysis of qualifying studies across intervention modality. The authors will classify the interventions for preschool children with ASD under three models: behaviour, multimodal developmental and communication focused. First, the authors will perform a systematic review. Then, the authors will conduct a meta-analysis by comparing the three models with various outcomes using an inverse variance method in a random effect model. The authors will synthesise each outcome of the studies for the three models using standardised mean differences.

Dissemination and ethics This study will identify each intervention's strengths and weaknesses. This study may also suggest what kinds of elements future intervention programmes for children with ASD should have. The authors strongly believe those findings will be able to translated into the clinical practices and patients and their family benefits. Review registration: PROSPERO CRD42011001349.