Police were alerted to the accident at 6.30am.
Police said Thossapol Yuenying, a resident of Yannawa district, was killed by the Bangkok-Aranyaprathet train.
Witnesses told police that Thossapol was seen coming into the station compound through a hole of the station's fence, which is used as a shortcut to get to the Airport Rail Link elevated train station above. But when he came through the fence, the Bangkok-Aranyaprathet train arrived and hit him.