千军万马的英文：
[Literal Meaning]
thousand/army/ten thousand/horse
a powerful army with thousands of horses

[解释]
形容兵马众多，声势好大。

[Explanation]
a mighty army

[例子]
远处的瀑布的声音很大，好像千军万马在奔跑。

[Example]
The sound of the falls are very loud, as if a mighty army were running.

[英文等价词]
a strong army with thousands of horses
large number of people