Improving communication specially through expressive language is the main goal that students with Autism Spectrum Disorder (ASD) need to acquire. Students with ASD can face difficulties when communicating with others because they have poor expressive language. They could not even form a full sentence without being trained. This study aimed to investigate the development of expressive language of ASD students from their teachers’ perspective. The researcher used mixed methods (qualitative and quantitative). The tools were a questionnaire and a semi-structured interview. The participants in this research were 30 male and female teachers from Yanbu and Jeddah, Saudi Arabia. The results showed that the expressive language of ASD students was very poor before joining speech therapy sessions. Using methods like group playing and modelling had a positive effect on developing ASD student’s expressive language.