This study explored self-injurious behavior (SIB) of autistic children in Vietnam through a cross-sectional design. 60 informants, including 57 parents and 3 caregivers completed the questionnaire on problem behavior consisting of aggression, self-injury, stereotyping, property destruction, other problem behaviors and their functions. Results revealed that children experienced all mentioned problem behaviors, especially self-injurious behavior. The topographies of self-injurious behavior of the children included head-hitting, head-scratching, head-banging, hair-pulling, face-hitting, face-puncturing with a pen, ear-scratching, lip-picking, hand-biting, hand-scratching, hand-pinching, and belly-scratching. The most common area of self-injurious behavior is the head. The functions of these problem behaviors were expressed in four types (social positive reinforcement, social negative reinforcement, automatic positive reinforcement and automatic negative reinforcement). Social positive reinforcement appeared as a prominent function. Out of these 57 children, 21 of them who were autistic with self-injurious behavior went through a functional assessment (FA) in which the four conditions known as attention, tangible items, escape from task/activities, automatic stimulation were tested. The results of functional analysis (FA) further indicated the correspondence between the FAST-R and FA outcome on function of problem behavior, especially self-injurious behavior. Results also showed that the prominent function of these self-injurious behaviors was social function. It means self-injurious behaviors usually occur within a condition of social interaction, especially, in this present study, in the tangible condition. The antecedent of self-injurious behavior is the removal of tangibles (e.g. food, preferred items). This paper contributes to our knowledge of self-injurious behavior of children with autism in Vietnam where empirical research of this field was still very rare.