如日中天的英文：
[Literal Meaning]
like/the sun/high noon
like the sun at high noon

[解释]
好像太阳正处于天顶。比喻事物正发展到十分兴盛的阶段。

[Explanation]
at the apex of one's power

[例子]
就在他的事业如日中天的时候，一场重病让他不得不彻底休息。

[Example]
When his career was flourishing like the green bay-tree, a serious illness made him rest eventually.

[英文等价词]
in one's or its prime
eat high on the hog

Like the sun in midsky-to be very influential
如日中天

In the full flush of success, nothing was an obstacle.
在成就如日中天时,其势锐不可当。