An overhead buffer device used for disposing in a semi-conductor factory includes a strut module and a plurality of buffer modules. The strut module disposed on the top wall of the factory has a horizontal beam and a plurality of overhead strut. The overhead strut is set on the horizontal beam and spaced arranged along the horizontal beam. The buffer modules are installed on the overhead strut respectively. Each buffer module has a plurality of buffers arranged in sequence and along a vertical direction. Each buffer is used for receiving one front opening unified pod (FOUP). Thus, the instant disclosure can be used for using the space of the factory efficiently. Besides, the instant disclosure also provides a wafer transport system having the overhead buffer device.