The color red is used to contribute to the gothic mood of the book.
When Jane finally decides to fight back against her bullying cousin John, she is described as “picture of passion.” She is sent to the red-room to separate her from the others, and so she can cool down. Jane hates the red-room because it is little used and frightening.
This room was chill, because it seldom had a fire; it was silent, because remote from the nursery and kitchens; solemn, because it was known to be so seldom entered. (ch 2)
One of the reasons Jane is afraid of the room is that when her uncle died he was laid to rest there, giving the room an even ghastlier feel. This and the overabundance of red in the room, as well as the stately furniture, contributes to the gothic mood of the book.