thank you so much , that's much clear, segregate is a kind of emotion word, while separate is a description without emotion.

I disagree slightly with Hannah, although she is mostly correct. It would be more accurate to say that "separate" means "to split something apart" whereas "segregate" means "to isolate from the main part of something." For example, in a prison, you might separate prisoners into groups for meal time, but a wise warden would segregate the more dangerous criminals from the others to prevent trouble.

Hi Yingwang, "separate" is a general word and is neutral (= it has no positive or negative connotations. / The word doesn't make you feel positive or negative.) "Segregate" is more specific and it has negative connotations. The specific meaning of "segregate" is to keep two groups of people apart and treat them differently. For example, African Americans used to be segregated from white Americans.