Could you help me with this? Could I express like this? Thank you very much!
The main color of the buildings is red，for red represents power,happiness,luck and prosperity in Chinese culture.

See a translation

Your sentence is grammatically perfect and does not sound awkward. You may like to make it flow better by re-wording it a bit.
Some suggestions:
"The buildings are mainly red, for red is the color of power, happiness, luck, and prosperity in Chinese culture."
"The main color of the buildings is red because red represents power, happiness, luck, and prosperity in Chinese culture."

In my opinion, "The buildings are mainly red..." sounds a bit better than "The main color of the buildings is red...," because the first is an active statement. However, either are correct.