Abstract: This work illustrates a newly developed non-invasive optical brain imaging. By comparision with commonly used brain imaging techniques, the feasibility and convenience are demonstrated for using optical brain imaging to investigate cortical activity for autistic children. Worldwide results on imaging autism with the optical technique are reviewed. Recent experimental data show that the hemodynamic responses in prefrontal cortex are different between children with autistic trait and normal controls in a task of the joint attention. Future comprehensive study with optical brain imaging on autistic brain activity and its inherent characteristics may provide reliable evidences for early autism diagnosis.