I am not sure about the following sentense:
success comes from both intelligence and persistent diligence.
Is it akward? Can I use it to express the meaning that people need to work hard even though they are talented?
Thanks for your help.
Your sentence is not awkward, though it is in a somewhat formal style.
I think 'consistent' works better than 'persistent'. To emphasise your "even though", I suggest:
"Success comes not only from intelligence, but also from consistent diligence"
Of course, if you wanted to put it less formally, you could say "People need to work hard even though they are talented"
PS. It may be a fine point, but I actually think "talent" is a more appropriate word than "intelligence" (they're not synonymous) : "Success comes not only from talent, but also from diligence" Of course you then lose the assonance of 'intelligence' and 'diligence', if you were trying for that.
I don't think you need the adjective "persistent" with "diligence", because someone who is diligent always works hard. And "both" could mean that intelligence could bring success, but so, also, could diligence, whereas I think your intended meaning is that you need intelligence and diligence.
If I'm right about your intended meaning, you could say something like Success comes from a combination of intelligence and diligence.
This reminds me of something said by Thomas Edison: Genius is one per cent inspiration and 99 per cent perspiration.