他说他将出国旅行。
would travel是travel的过去将来时形式。
过去将来时由
助动词would加动词的原形构成，表示从过去某时看来将要发生的动作或存在的状态，如：
He said that he would wait for us at the bus stop.
She hoped that they would meet again someday.
过去将来时可以用would加动词原形，be going to的过去时加动词原形，be about to的过去时加动词原形，be on the point of的过去时加
动名词，be due to的过去时加动词原形，be to的过去时加动词原形表示。
There was going to be a thunderstorm.
She waited until he was about to leave.
She was on the point of leaving when we came in.
The ship was due to leave at midnight.
They said that they were leaving for New England soon.
She said she was to take up the position.
希望我能帮助你解疑释惑。