The braincase of Phuwiangosaurus sirindhornae has been discovered in the Early Cretaceous Sao Khua Formation, which is well preserve and nearly completely. On the other hand, the details of internal structure of these parts are poorly known in the sauropod dinosaur. Herein, we present comparative morphology studies of the braincases interior, or endocast, of P. sirindhornae. It was CT scanned, and 3D rendering of the cranial endocast was generated. The cranial endocast shows the general morphology of other sauropods being bulbous, anteroposteriorly short and transversely wide, and pituitary body is relatively long and oriented caudoventrally