Is This Sentence Correct: His Age Is Old.

He is old.

It is not "his age" that is old but the man himself.

LouiseTHe is old.It is not "his age" that is old but the man himself.

Sorry ,i don't understand .

Sorry - I did not mean to confuse you.

X is old
He is old.
His dog is old.
His wife is old.
But not "his age" is old.

The correct sentence is "He is old".

But if I want to say " The number of his age is high " What's the correct way???

His age is high. (correct but sounds a bit strange too me)

Perhaps you could use something like this

He didn't get the job because of his old/high age.

hyundaisantafe126789But if I want to say " The number of his age is high " What's the correct way???

No, that's not good. If you have to use "age" then you could say

He's of old age.