This article describes the application of an experimental functional analysis of behavior to determine the functions of behavior in a child with autism spectrum disorder (ASD). Problem behavior is always a current aspect in the development, growth and education of children with ASD and is the focus of attention of researchers around the world. Neglecting problem behavior leads to negative outcomes in the development of mental processes, qualities, personality traits and social skills. The research methodology of behavior functions, the development and application of training is a very rigorous process and requires the presence of professional and personal qualities from a specialist, the support, understanding and work of the familiar circle. In this article the relevance of the study is argued, a case of problematic behavior is presented, a methodology for studying the functions of the target behavior, a training model developed and applied using the experimental functional analysis of the behavior. Selecting a strategy for correcting problem behavior is always done taking into account the skills developed in a child with ASD.