Autism is a neurological and developmental disorder caused due to malfunction in brain development. It is an emerging field in child psychiatry in the world. Moreover in developing countries like India there is a need for awareness regarding autism among the medical professionals. The proposed research was to investigate variation in the physiological parameters between autism and normal children. Eighty Indian Children subjects (40 Normal and 40 Autism) from a special school participated voluntarily in this study with age group ranging from 8–13 years. Photoplethysmograph (PPG) and galvanic skin response (GSR) signal were recorded during mental task through clue cards with visual like alphabets, numbers, fruits, colors, and animals. The experiment was performed during the forenoon session for both normal and autism children. The task performance is measured by calculating the error of commission and omission. PPG and GSR signal are pre-processed, and dicrotic notch, heart rate (HR) and GSR feature are extracted from the acquired signal. The nonparametric Mann- Whitney-U tests were performed. The heart rate, dicrotic notch, and GSR were significantly (p<0.05) high for the autism group when compared to control children. The current study result implies that PPG and GSR signals recorded for the autistic children are high in comparison with normal children.