Clinical protocols are crucial to quality health care delivery for children with autism spectrum disorder (ASD). This paper discusses the principles for designing clinical protocols including autistic assessment, diagnosis and intervention. Five principles are proposed and verified with design scenarios covering cognition, emotion, motor and societal capabilities during cognitive development. it is noticed giving priority to autistic children that features of autistic symptoms are effectively induced and also heavily correlated with impaired social capabilities. This paper paves the way for principles of clinical protocols design for developmental and cognitive issues such as ASD.