This study is an instructional criticism on mathematics class in special education field to explore how teachers implement the curriculum and what are the characteristics of the class. For this study, after observing the lesson, I collected data such as class video, teacher interview, class instruction plan, class observation records, fellow teachers interview, and criticized the class by describing and interpreting. Before criticizing the class, I mentioned the concept, necessity, value and possibility of instructional criticism and explained the class in detail. And criticized the curriculum was reorganized into a functional curriculum, a class in which all students participated together, the development of subjectivity expertise, and the growth through reflection. Finally, the meaning of instructional criticism in the field of special education was discussed based on the researcher's experience.