One of utterences used by autistic children in communicating their ideas is expressive speech act. This paper aims to describe the forms and functions of expressive speech acts in the speech of autistic children. This study used qualitative approach. The data obtained were the speech of autistic children, constructing the forms and functions of expressive speech acts. The data were collected by using recording and observation techniques. To analyze the data, the interactive model analysis was deployed. The analysis resulted in two major findings. Firstly, the forms of expressive speech acts in the speech of autistic children included the statement of happiness, unhappiness, and gratitude. Secondly, the functions of expressive speech acts in the speech of autistic children were to express happiness, anger, and fear.