The aim of this study is to describe the mathematical thinking process of autistic students in terms of gesture, using a qualitative approach. Data collecting is conducted by using 3 (three) audio-visual cameras. During the learning process, both teacher and students' activity are recorded using handy cam and digital camera (full HD capacity). Once the data is collected (the recording process is complete), it will be analyzed exploratively until data triangulation is carried out. Results of this study describes the process of mathematical thinking in terms of a gesture of students with autism in three categories, namely correctly processed, partially processed, and contradictory processed. Correctly processed is a series of actions to solve the problems that are processed properly marked with a matching gesture, partially processed is a series of actions to resolve problems with partially processed properly marked with discrepancy gesture, while contradictory processed is a series of actions to solve the problems that are processed incorrectly marked with the dominance of discrepancy gesture. Matching gesture demonstrate the suitability of movement or facial expressions when observing, pointing, and uncover/calling the object being observed, while the discrepancy gesture indicates a mismatch movements or facial expressions when observing, pointing, and uncover/calling the object being observed.